ORIGINAL   COMMUNICATIONS 

EIGHTH   INTERNATIONAL 

CONGRESS 
OF  APPLIED  CHEMISTRY 


Washington  and  New  York 
September  4  to  13,  1912 


SECTION    III6. 
EXPLOSIVES 


VOL.  IV 


ORIGINAL   COMMUNICATIONS 

EIGHTH   INTERNATIONAL 

CONGRESS 
OF  APPLIED  CHEMISTRY 


Washington  and  New  York 
September  4  to  13,  1912 


SECTION   III6. 
EXPLOSIVES 


VOL.    IV 


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THE     RUMFORD     PRESS 
CONCORD- N'H-U-8. A- 


ORIGINAL   COMMUNICATIONS 

TO  THE 

EIGHTH  INTERNATIONAL  CONGRESS 

OF 

APPLIED    CHEMISTRY 


APPROVED 

BY  THE 

COMMITTEE  ON  PAPERS  AND  PUBLICATIONS 

IRVING  W.  FAY.  CHAIRMAN 
T.  LYNTON  BRIGGS  JOHN  C.  OLSEN 

P.  W.  FRERICHS  JOSEPH  W.  RICHARDS 

A.  C.  LANGMUIR  E.  F.  ROEBER 

A.  F.  SEEKER 


246079 


SECTION£]in&.— EXPLOSIVES 


EXECUTIVE  COMMITTEE 
President:  CHARLES  E.  MUNROE,  Ph.D. 
V ice-President:  THOMAS  M.  CHATARD,  Ph.D.,  LL.D. 
Secretary:  WALTER  O.  SNELLING,  Ph.D. 

CHARLES  L.  REESE,  Ph.D. 
CHARLES  F.  MCKENNA,  Ph.D. 


SECTIONAL  COMMITTEE 


HENRY    L.    ABBOTT,    LL.D., 
Brig.  General,  U.  S.  A. 

A.  S.  BARKER,  Rear  Admiral, 
U.  S.  Navy. 

CHARLES  P.  BEISTLE,  B.S. 

MARCUS  BENJAMIN,  Ph.D., 
Sc.D.,  LL.D. 

A.  A.  BRENEMAN,  M.Sc. 

W.  H.  BUELL,  Ph.B. 

PAUL  BUTLER 

A.  M.  COMEY,  Ph.D. 

B.  W.  DUNN,  Colonel,  U.  S.  A., 

D.S. 

F.  H.  GUNSOLUS,  C.E. 
CLARENCE  HALL 

and  the  Sectional 


A.  L.  KIBLER,  M.S. 

W.    I.    KOLLER 
M.    F.    LlNDSLEY 

FREDERICK  J.  M.  MASURY 

HUDSON  MAXIM 

G.  W.  PATTERSON,  B.S. 

R.  S.  PENNIMAN,  B.S. 

C.  G.  STORM,  M.S. 

JOSEPH  STRAUSS,  Commodore, 

U.  S.  N. 
ERASMUS  M.   WEAVER,   Brig. 

General,  U.  S.  A. 
JOHN  P.  WISSER,  Col.,  U.  S.  A. 
EDWARD  C.  WORDEN,  M.A. 

Executive  Committee 


VOLUME   4 
SECTION  III6 .— EXPLOSIVES 

CONTENTS 

BBISTLE,  CHARLES  P. 

The  Determination  of  Exudation  of  Nitroglycerin  from  Dynamite          7 

BENJAMIN,  MARCUS. 

A  Convenient  Method  for  Testing  the  Color  of  Explosives 9 

BROADBENT,  ALFRED  L.,  and  SPARRE,  FIN. 

Nitration  of  Anisol  to  Tri  Nitro-Anisol 15 

BRUNSWIG,  DR.  H.  VON. 

Neue  Initialzundung  fur  Sprengstoffe 10 

CHATARD,  THOMAS  M. 

The  Misuse  of  Explosives 23 

DAUTRICHE,  H.     See  TAFFANEL,  J. 

DELEPINE,  M.  MARCEL. 

Sur  L' Inflammability  de  L'Acetylene  Melange  de  30%  d'Air 
Environ 25 

FLURSCHEIM,  DR.  BERNHARD. 

Tetranitroaniline,  a  new  High  Explosive 31 

GOPNER,    VON    C. 

Auszug  aus  dem  Vortrage:  Die  Internationale  Regelung  der 
Vorschriften  uber  den  Post-,  Eisenbahn-  und  Seetransport  explosiver, 
leicht  brennbarer,  aetzender,  etc.,  Produkte 35 

HIBBERT,  HAROLD. 

The  Preparation,  Crystalline  Structure  and  Physical  Properties  of 
the  Two  Forms  of  Solid  Nitroglycerin • 37 

HYDE,  A.  L. 

Boiling  Points  of  Solutions  of  Nitroglycerin 59 

HYDE,  A.  L. 

Separation  of  Nitroglycerin  from  Nitrosubstitution  Compounds  ...         69 

MASLAND,  WALTER  E.,  and  SPARRE,  FIN. 

Abstract  of  Paper  on  Hydrolysis  of  Tri-Nitro-Anisol  by  Alkalies 
and  Water 77 

MOIR,  JAMES. 

A  Plea  for  Improvement  in  the  Methods  of  Chemical  Testing  of 
Mining  Explosives 

ROBINSON,  ARTHUR  LEE. 

Detonator  Troubles  Experienced  in  the  Construction  of  the  Isthmian 
Canal 85 

5 


6  Original  Communications:  Eighth  International 

SNELLINQ,  WALTER  O. 

Improved  Densimeter 105 

SPARRE,  FIN.    See  BROADBENT,  ALFRED  L. 

STORM,  C.  G. 

The  effect  of  the  Nitrotoluenes  on  the  Determination  of  Nitroglycerin 
by  Means  of  the  Nitrometer 117 

TAFFANEL,  J.,  and  DAUTRICHE,  H. 

Recherches  de  la  Station  d'essais  de  Lifvin  sur  les  explosifs  de  sarete 
pour  mines  grisoutcuses  et  poussiereuses 127 

WEBER,  H.  C.  P. 

On  a  Modified  Form  of  Stability  Test 147 

WlERMAN,  S.  A. 

A  New  Stability  Test  for  Nitrocellulose  Powders 157 


Abstract 

THE   DETERMINATION    OF    EXUDATION    OF   NITRO- 
GLYCERIN  FROM  DYNAMITE 

BY  CHARLES  P.  BEISTLE 
South  Amboy,  N.  J. 

The  compression  method  of  determining  the  exudation  of  dyna- 
mite was  found  to  give  results  which  depended  upon  the  nature 
of  the  absorbent  materials  used,  and  did  not  agree  with  the  40° 
oven  tests,  which  simulate  the  most  severe  conditions  likely  to 
be  met  with  in  transportation  under  normal  conditions. 

By  subjecting  a  sample  of  dynamite  to  centrifugal  force,  as 
suggested  by  Mr.  T.  J.  Wraempelmeier,  in  a  centrifugal  machine, 
the  cups  of  which  describe  a  circle  of  7  inches  radius,  rotated  at  a 
speed  of  600  revolutions  per  minute  for  one  minute,  results  were 
obtained  which  checked  the  40°  tests.1  This  method  of  testing 
affords  a  rapid  and  effective  means  of  determining  the  exudation 
of  nitroglycerin  from  dynamite,  and  has  given  highly  satisfactory 
results,  so  that  now  practically  no  leaky  dynamite  is  being  manu- 
factured in  this  country  or  Canada. 


Report  of  the  Chief  Inspector,  Bureau  for  the  Safe  Transportation  of 
Explosives,  Feb.,  1909,  p.  27. 

7 


A  CONVENIENT  METHOD  FOR  TESTING  THE  COLOR 
OF  EXPLOSIVES 

BY  MARCUS  BENJAMIN 
Washington,  D.  C. 

Some  years  ago  I  was  consulted  as  to  whether  there  was  any 
definite  scientific  method  by  which  various  ordinary  colors  or 
shades  could  be  analyzed,  that  is,  have  their  composition  deter- 
mined in  exact  terms  from  which  the  original  color  or  shade  could 
again  be  synthesized  or  duplicated  without  any  possibility  of 
error.  After  some  study  I  came  to  the  conclusion  that  the  practi- 
cal solution  of  this  problem  could  be  best  worked  out  along  the 
lines  of  the  valuable  researches1  made  by  Ogden  N.  Rood,  long 
professor  of  physics  at  Columbia  University  and  perhaps,  after 
Chevreul,  the  greatest  authority  on  color. 

Rood  determined  with  great  exactness  the  wave  lengths  of  the 
spectrum  colors  which  he  adopted  as  standards  and  then  found 
corresponding  pigments  easily  purchasable  in  the  open  market 
that  might  be  used  for  comparison.  According  to  determinations 
made  in  the  physical  laboratory  of  Columbia  College,  therefore, 
the  wave  lengths  of  the  five  standard  colors  chosen  expressed  in 
microns  were  as  follows:  red,  0.644;  orange,  0.614;  yellow,  0.585; 
green,  0.521;  and  blue,  0.425. 

After  accepting  these  standards  it  became  necessary  to  make 
them  available  for  practical  use.  That  is  to  say,  if  we  wanted  to 
prove  that  the  color  cinnabar,  derived  from  the  mineral  of  that 
name,  consisted  of  exactly  78  parts  of  red  and  22  parts  of  orange, 
we  must  have  some  convenient  colors  to  compare  it  with  for  the 
reason  that  a  spectroscope  is  not  always  accessible  and,  moreover, 
it  is  an  instrument  that  requires  a  certain  amount  of  skill  for  ma- 
nipulation. Accordingly  for  this  part  of  the  problem  advantage 
was  taken  of  the  investigations  made  by  J.  Clark  Maxwell.  This 
eminent  scientist  used  for  his  analyses  of  color  a  series  of  color 
discs  which  he  rotated  on  a  wheel.  These  color  discs  consisted  of 

!On  a  Color  System.    Amer.  Jour.  Sci.,  Vol.  44,  1892,  pp.  263-270. 

9 


10  Original  Communications:  Eighth  International        [VOL. 

circular  pieces  of  pasteboard  coated  with  colored  paper  or  painted 
with  colored  pastes.  By  overlapping  these  discs  within  a  gradu- 
ated circle  and  rapidly  rotating  them  on  a  wheel  so  as  to  produce 
an  impression  of  a  single  mass  of  color,  they  could  be  made  to 
correspond  to  any  desired  color,  and  especially  so  when  a  small 
piece  of  material  of  the  color  to  be  matched  was  placed  in  front  of 
the  discs,  that  is,  near  the  center  of  the  rotating  instrument,  which, 
though  usually  a  wheel,  was  sometimes  a  top. 

Therefore  it  is  easily  possible  by  means  of  the  Maxwell  color 
wheel  to  determine  the  various  colors  in  terms  of  five  standard 
colors  obtained  from  the  spectrum,  together  with  black  and  white. 
The  five  color  discs  selected  were  prepared  by  mixing  the  best 
(1)  English  vermilion;  (2)  mineral  orange;  (3)  light  chrome  yellow; 
(4)  emerald  green;  and  (5)  artificial  ultramarine  blue — all  pigments 
readily  purchasable  in  any  paint  store — with  a  thick  solution  of 
gum  arabic  in  water  until  it  had  a  consistency  equal  to  that  of 

011  paint  and  applying  it  to  the  cardboard.    Light  cardboard  or 
heavy  drawing  paper  can  be  used.    The  white  was  cut  from  the 
purest  white  cardboard  obtainable  and  the  black  one  was  made  by 
painting  a  white  disc  with  a  mixture  of  the  best  lampblack  in  an 
alcoholic  solution  of   shellac.     The   disc  when   finished   should 
have  an  even,  firm,  and  dull  surface.    The  best  size  of  which  to 
make  the  discs  is  from  three  to  five  inches  in  diameter. 

Within  a  comparatively  short  time  the  desirability  of  some 
standard  measurement  for  colors  became  necessary  in  the  labora- 
tory of  the  U.  S.  Bureau  of  Mines  in  connection  with  the  work  of 
analyzing  explosives,  particularly  dynamite  and  explosives  of 
the  class  now  so  largely  used  in  mines  and  designated  "permissible 
explosives."1 

Prof.  Charles  E.  Munroe,  consulting  expert  to  the  Bureau, 
called  attention  to  the  method  which  has  just  been  described, 
and  on  his  recommendation  it  was  adopted.  He  has  since  ad- 
vised me  that  it  "has  been  regularly,  I  might  properly  say  officially, 

*An  explosive  is  called  a  permissible  explosive  when  it  is  similar  in  all 
respects  to  the  sample  that  passed  certain  tests  by  the  national  Bureau  of 
Mines,  and  whten  it  is  used  in  accordance  with  the  conditions  prescribed  by 
that  bureau.  Investigations  of  Explosives  used  in  Coal  Mines.  Bulletin 
15,  Bureau  of  Mines,  1912,  p.  192. 


iv]  Congress  of  Applied  Chemistry  11 

used  in  recording  the  characteristic  color  of  the  explosives  sub- 
mitted for  testing."  Also  that  the  adoption  of  this  method 
"greatly  improved  the  precision  of  their  descriptions." 

As  this  method  has  never  before  been  used  in  connection  with 
explosives,  and,  as  I  understand,  no  description  has  ever  been 
published,  I  have  sought  from  Doctor  Walter  O.  Snelling,  the 
chemist  in  charge  of  this  work  in  Pittsburgh,  for  information  con- 
cerning it,  and  from  facts  kindly  furnished  by  him  I  have  pleasure 
in  presenting  the  following  brief  description  of  the  method  used 
in  his  laboratory. 

As  is  generally  known  a  part  of  the  work  of  the  Bureau  of  Mines 
consists  in  the  study  of  explosives,  including  the  elaboration  of  a 
series  of  tests  by  which  explosives  that  can  be  safely  fired  in  a 
mine  in  the  presence  of  firedamp  could  be  separated  from  those 
which  cannot  be  so  fired  without  causing  explosion.  The  work 
of  testing  an  explosive  covers  a  long  series  of  physical  and  chemical 
examinations  and  a  large  number  of  practical  tests  within  a  steel 
gallery,  where  the  normal  conditions  of  a  mine,  in  regard  to  the 
presence  of  gas,  etc.,  may  be  imitated.  It  soon  became  evident 
that  even  when  an  explosive  had  passed  all  of  the  required  tests, 
it  might,  at  some  subsequent  time,  become  so  changed  in  composi- 
tion by  the  manufacturer  (as  the  market  price  of  the  different 
constituents  varied)  as  to  be  no  longer  as  safe  as  was  the  original 
sample  furnished  to  the  Bureau.  Accordingly,  Doctor  Snelling 
set  about  finding  a  method  by  which,  through  the  aid  of  chemical 
analysis  and  a  careful  study  of  physical  characteristics,  it  might 
be  possible  to  detect  any  changes  in  the  composition  of  an  ex- 
plosive, and  he  began  with  comparing  the  report  of  the  original 
explosive  with  the  results  obtained  from  samples  which  are  col- 
lected from  time  to  time  by  mining  engineers  in  mines  where  the 
explosive  was  actually  in  use. 

Doctor  Snelling  devised  an  exact  means  of  determining  the 
absolute  density  of  an  explosive,  etc.,  and  arranged  the  work  of 
the  chemical  laboratory  in  such  a  way  as  to  make  the  examina- 
tion of  the  chemical  constituents  present  in  an  explosive,  and 
their  percentages,  a  matter  of  ready  determination.  The  color 
was  a  factor  that  did  not  admit  of  easy  classification,  and  yet  it 
was  recognized  that  a  change  in  color  of  the  explosive  would  be 


12  Original  Communications:  Eighth  International        [VOL. 

one  of  the  changes  that  would  result  from  a  difference  in  composi- 
tion and  one  that  would  be  most  quickly  detected.  Therefore  it 
seemed  eminently  desirable  that  this  point  should  be  carefully 
considered. 

From  paint  manufacturers  a  series  of  charts  showing  certain 
standard  colors  was  obtained,  and  for  a  time  an  attempt  was 
made  to  report  the  color  of  explosives  by  comparing  them  with  the 
nearest  color  sample  that  could  be  obtained. 

It  was  at  this  point  that  Professer  Munroe  called  Doctor  Snell- 
ing's  attention  to  the  plan  of  using  the  color  wheel  as  suggested 
in  the  earlier  part  of  this  article.  Doctor  Snelling  readily  recog- 
nized the  value  of  this  method  and  constructed  a  set  of  color  discs, 
six  in  number,  as  follows:  black,  white,  red,  yellow,  blue,  and 
green.  His  discs  were  20  centimeters  in  diameter  and  were  so 
arranged  as  to  be  mounted  upon  an  ordinary  metallic  centrifuge, 
such  as  is  made  by  Williams,  Brown,  and  Karle  of  Philadelphia, 
Pennsylvania. 

The  chemists  in  the  laboratory  of  the  Bureau  of  Mines  soon 
acquired  the  ability  of  very  readily  and  quickly  determining  the 
color  of  any  explosive  in  terms  of  the  percentage  of  the  color  discs 
in  use,  starting  in  general  from  a  known  definite  color  composition 
of  the  color  which  appeared  nearest  to  the  one  present  in  the 
explosive.  For  example,  if  the  explosive  were  a  light  grayish- 
yellow,  the  color  wheel  would  be  set  to  the  percentage  of  primary 
colors  given  in  the  standard  previously  determined,  and  then 
adjustment  would  be  made  until  the  color  corresponded  in  every 
respect  to  the  sample  of  explosive  under  examination. 

Subsequently  Doctor  Snelling  devised  various  minor  improve- 
ments in  the  method  of  examination.  These  included  a  movable 
celluloid  cover  over  the  top  of  the  discs  to  protect  them  from  dirt, 
and  the  use  of  a  brass  plate  as  the  bed  plate  on  which  the  discs 
should  rest  with  graduations  on  its  outer  edge,  so  that  the  percent- 
age of  any  color  disc  which  is  present  could  be  more  easily  read. 
He  also  found  it  to  his  advantage  to  use  larger  color  discs  and 
found  those  25  centimeters  in  diameter  the  most  satisfactory. 
The  brass  plate  on  which  these  rest  is  29  centimeters  in  diameter, 
which  allows  an  annular  space  two  centimeters  wide  for  gradua- 
tion, and  a  brass  frame  29  centimeters  in  diameter,  carrying  a 


iv]  Congress  of  Applied  Chemistry  13 

plate  of  celluloid  which  serves  as  the  cover  for  the  apparatus  and 
will  revolve  with  the  color  discs. 

By  such  means  it  is  found  possible  to  determine  in  a  most 
simple  and  exact  manner  the  color  relations  of  the  explosives 
which  are  under  examination. 


NITRATION    OF    ANISOL    TO    TRI-NITRO-ANISOL 

BY  ALFRED  L.  BROADBENT  AND  FIN  SPARRE 
Wilmington,  Delaware 


Tri-nitro-anisol,  the  tri-nitro  derivative  of  anisol, 
may  be  looked  upon  as  the  methyl  ester  of  picric  acid.  Theo- 
retically, four  isomers  of  this  ester  are  possible,  but  only  one 
appears  to  be  known,  viz.,  2,  4,  6-tri-nitro-anisol.  The  chemical 
literature  treating  of  the  preparation  of  this  compound  from  anisol 
is  very  scant.  Beilstein,  Organische  Chemie,  II-2-691,  states 
that  it  is  formed  by  treating  anisic  acid  or  anisol  with  sulphuric- 
nitric  acid,  quoting  an  article  by  Cahours,  Annalen  der  Chemie 
1868,  69,  238.  The  same  statement  occurs  in  Watts'  Dictionary 
of  Chemistry,  and  V.  Meyer  and  P.  Jacobson's  Lehrbuch  der 
Organischen  Chemie  contains  nothing  more  on  this  subject.  The 
article  by  Cahours  merely  states  that  tri-nitro-anisol  is  formed 
by  the  action  of  a  mixture  of  concentrated  nitric  and  sulphuric 
acids  on  anisol. 

This  investigation  was  undertaken  owing  to  the  aforesaid 
absence  of  information  in  the  literature  and  to  considerable 
difficulty  experienced  in  preliminary  work  on  the  same  subject. 
The  anisol  was  made  by  a  method  described  by  Kolbe  (Journal 
fur  praktische  Chemie,  11-27-424)  through  reaction  between 
sodium  phenylate  and  sodium  methyl  sulphate: 

C6H5ONa+CH3NaS04  =  CeHsOCHs+NasSO^ 

Although  there  seemed  to  be  no  apparent  reason  why  the 
nitration  of  anisol  to  tri-nitro-anisol  should  be  accompanied  by 
extraordinary  difficulties,  preliminary  experiments  indicated  this 
to  be  the  case.  Nitric  acid  alone  as  well  as  nitric-sulphuric  acid 
in  a  variety  of  concentrations  and  proportions  were  tried  at 
lower  and  higher  temperatures  with  but  indifferent  success.  When 
the  acids  were  too  dilute  the  nitration  was  incomplete,  while 
with  acids  of  higher  concentration  the  reaction  was  quite  violent, 
abundant  and  suffocating  nitrous  fumes  being  evolved,  and  a 

15 


16  Original  Communications:  Eighth  International        [VOL. 

product  resulted  which  was  never  quite  free  from  the  lower  nitro- 
anisols  and  which  was  invariably  contaminated  with  oxidation 
products.  It  was  found,  however,  that  as  soon  as  one  N02  group 
was  introduced,  further  nitration  could  be  readily  accomplished 
in  the  usual  manner.  This  fact  led  to  an  investigation  of  the 
possibilities  of  nitrating  anisol  to  mono-nitro-anisol  and  the 
subsequent  nitration  of  the  latter.  It  was  soon  found  that  the 
difficulties  which  militated  against  the  success  of  the  one-step 
nitration  were  met  with  in  this  case,  namely,  low  yields  contami- 
nated with  by-products  of  the  reaction  resulting  from  the  oxidation 
of  the  side-chain.  Experiments  were  next  carried  out  to  determine 
the  possibilities  of  nitrating  anisol  sulphonic  acid,  the  latter 
being  prepared  by  dissolving  anisol  in  concentrated  sulphuric 
acid.  Although  a  very  pure  product  of  tri-nitro-anisol  was  readily 
obtained  the  method  was  unsatisfactory  owing  to  the  low  yields, 
which  in  no  case  exceeded  40%  of  the  theoretical. 

In  view  of  the  foregoing  indifferent  results  it  was  decided  to 
investigate  more  fully  the  one-step  nitration  with  mixed  acids. 
The  results  were  most  gratifying,  it  being  found  that  an  excellent 
yield  of  tri-nitro-anisol  of  a  high  degree  of  purity  could  be  quite 
readily  obtained. 

The  nitration  is  best  carried  out  by  placing  350  gms.  of  a  mixed 
acid  prepared  by  adding  130  gms.  of  nitric  acid  of  S.  G.  1.52  to 
220  gms.  of  concentrated  sulphuric  acid,  S.  G.  1.84  in  a  400  cc. 
beaker  surrounded  by  an  ice-salt  freezing  mixture.  The  liquid 
within  the  beaker  is  agitated  by  a  propeller-shaped  stirrer  (driven 
by  a  belt  connected  with  a  water  motor)  revolving  at  the  rate  of 
about  250  revolutions  per  minute,  and  stirring  downwards. 
The  temperature  of  the  liquid  is  recorded  by  a  thermometer 
placed  in  the  beaker  in  such  a  manner  as  not  to  interfere  with 
the  stirring.  When  the  temperature  of  the  acid  reaches  — 5°C. 
the  anisol  (30  gms.)  is  slowly  introduced  from  a  separatory  funnel 
drop  by  drop  at  such  a  rate  that  the  temperature  of  the  liquid 
in  the  beaker  does  not  exceed  0°C.  The  stem  of  the  separatory 
funnel  should  be  drawn  out  to  facilitate  the  introduction  of  the 
anisol  in  very  small  drops.  With  the  above  quantities  from  two 
to  three  hours  are  required  for  introducing  the  anisol. 

It  is  absolutely  essential  that  the  temperatures  be  kept  below 


iv]  Congress  of  Applied  Chemistry  17 

0°C.  at  the  beginning  of  the  experiment.  At  higher  temperatures 
oxidation  as  well  as  nitration  occurs,  and  the  reaction  is  most 
vio  ent,  combustion  of  the  anisol  having  resulted  in  some  instances. 

After  adding  the  anisol  the  temperature  is  slowly  raised  to  65° 
-70°C.  and  kept  at  this  point  for  twenty  minutes,  stirring  continu- 
ally. The  mixture  is  then  cooled  (or  poured  into  four  or  five 
volumes  of  water),  whereupon  the  lemon-yellow  colored  tri- 
nitro-anisol  separates  in  a  solid  crystalline  cake.  The  latter  is 
separated  from  the  acid  and  purified  by  heating  first  with  water 
at  70°-80°C.  (at  which  temperature  it  is  liquid),  cooled,  the  water 
withdrawn  and  treatment  repeated  with  a  2%  solution  of  sodium 
carbonate,  followed  by  two  more  treatments  with  water.  After 
the  final  washing  the  water  is  removed  and  the  product  dried 
between  filter  paper  and  in  a  desiccator.  The  yield  of  tri-nitro- 
anisol  is  55-60  gms.,  equal  to  about  85%  of  the  theoretical  from 
the  anisol. 

The  tri-nitro-anisol  thus  obtained  melts  between  64°  and  65°C. 
It  is  nearly  insoluble  in  water,  but  is  slowly  hydrolized  by  the 
latter  nto  methyl  alcohol  and  picric  acid.  It  is  quite  soluble  in 
alcoho  and  ether,  and  dissolves  very  readily  in  acetone.  Its 
specific  gravity  is  1.408  at  20°C. 

The  above  experiments  were  carried  out  at  the  Experimental 
Stat  on  of  the  E.  I.  duPont  deNemours  Powder  Company. 


NEUE     INITIALZUNDUNG     FUR     SPRENGSTOFFE 

VON  DR.  H.  BRUNSWIG 
Berlin-Steglitz,  Germany 

Seit  einigen  Jahren  kommen  Ziindschniire  in  den  Handel, 
deren  Sprengstoffseele  bei  geeigneter  Initiierung  detoniert.  Be- 
festigt  man  eine  solche  Ziindschnur  auf  einer  Bleiplatte  und 
detoniert  man  die  Ziindschnur  mit  Hiilfe  einer  Sprengkapsel,  so 
entsteht  auf  der  Bleiplatte,  dort,  wo  die  Ziindschnur  auflag, 
eine  kanalformige  Vertiefung.  Man  beobachtet  diese  Explosions- 
wirkung  regelmassig  bei  Bestimmung  der  Detonationsgeschwindig- 
keit  von  Sprengstoffen  nach  der  Methode  von  Dautriche, 
bemerkt  aber  zugleich  eine  andere  Erscheinung,  welche  in  ver- 
schiedener  Richtung  Interesse  beansprucht. 

Bei  Bestimmung  der  Detonationsgeschwindigkeit  von  Spreng- 
stoffen nach  Dautriche  kommt  es  bekanntlich  darauf  an,  den 
Treffpunkt  von  zwei  in  entgegengesetzter  Richtung  in  der  Deto- 
nations-ziindschnur  verlaufenden  Explosionswellen  auf  der  unter- 
gelegten  Bleiplatte  festzuhalten.  Es  ist  leicht,  diesen  Treffpunkt 
zu  erkennen;  denn  der  von  den  zwei  aufeinanderstossenden 
Detonationswellen  auf  der  Bleiplatte  hervorgerufene  Eindruck 
hat  einen  vollig  anderen  Charakter  als  der  von  der  Detonations- 
ziindschnur  selbst  erzeugte.  Der  Eindruck,  welchen  die  aufei- 
nanderstossenden Detonationswellen  bewirken,  gleicht  einem 
Messerschnitt,  der  rechtwinklig  zur  Ziindschnur  gefiihrt  wurde; 
durch  diese  dagegen  wird  eine  Vertiefung  hervorgerufen,  die 
unterhalb  der  Ziindschnur  mit  ihr  parallel  verlauft  und  einen 
halb  zylindrischen  Kanal  bildet.  Die  schnittartige  mechanische 
Wirkung  der  aufeinanderstossenden  Detonationswellen  ist  be- 
sonders  gut  auf  der  Riickseite  der  Bleiplatte  zu  erkennen.  Die 
Querstellung  dieser  Druckwirkung  ist  geradezu  charakteristisch 
fur  aufeinanderstossende  Detonationswellen;  sie  ist  eine  Folge 
der  ungeheuren  Geschwindigkeit,  mit  welcher  zwei  Gasschichten 
hier  zusammentreffen  und  sich  seitlich  ausbreiten.  Wenn  die 
Fortpflanzungsgeschwindigkeit  der  Detonation  in  Sprengstoffen, 

19 


20  Original  Communications:  Eighth  International  [VOL. 

soweit  uns  bekannt,  hochstens  8  km  pro  Sekunde  betragt,  so  kann 
sie  in  Treffpunkt  der  entgegengesetzt  gerichteten  Detonations- 
wellen,  relativ  zu  einander  gemessen,  das  Doppelte,  also  16  km 
pro  Sekunde  erreichen. 

Eine  merkwiirdige  Eigenschaft  des  Treffpunktes  aufeinander- 
stossender  Detonationswellen,  auf  welche  mein  Vortrag  die 
Aufmerksamkeit  lenken  mochte,  ist  seine  kraftige  Initialwirkung 
auf  andere  Sprengstoffe.  Was  die  Ursache  des  iiberraschend  gros- 
sen  Initiiervermogens  der  auf einanderstossenden  Detonationswellen 
ist,  ob  ihre  eigentumliche,  soeben  gekennzeichnete  seitliche  Aus- 
breitung,  oder  ihre  ungewohnlich  grosse  Verdichtung  im  Treff- 
punkt, lasst  sich  zurzeit  nicht  entscheiden,  zumal  man  Spreng- 
stoffe mit  Detonationsgeschwindigkeiten  von  10  bis  20  km  in  der 
Sekunde  nicht  kennt.  Bis  auf  weiteres  kann  man  annehmen, 
dass  eine  spezifische  Wirkung  der  aufeinanderstossenden  Deto- 
nationswellen vorliegt  und  dass  man  sich  iiberhaupt  hier  vor  einem 
neuen  Phanomen  befindet.  Es  ist  mit  der  Moglichkeit  zu  rechnen, 
dass  die  aufeinanderstossenden  Detonationswellen  noch  andere 
technisch  wertvolle  Fahigkeiten  besitzen,  die  bei  Sprengstoffen 
nicht  in  dem  Grade  beobachtet  werden. 

Was  den  Gegenstand  dieses  Vortrages  bildet,  betrifft  also  eine 
neue  Art  der  Initiierung  von  Sprengstoffen,  die  von  alien  bis- 
herigen  Ztindungen  einschliesslich  der  Sprengkapselztindung 
wesentlich  abweicht.  Die  neue  Ztindungsweise  stiitzt  sich  auf  das 
bisher  tibersehene  Initiiervermogen  des  Treffpunktes  zweier  auf- 
einanderstossenden Detonationswellen.  Bisher  war  bekannt,  dass 
der  Grad  der  Initiierung  eines  gegebenen  Initialsprengstoffes 
bei  gegebener  Anordnung  desselben  abhangt  von  dessen  Menge; 
aber  man  wusste  nicht,  dass  mit  der  gleichen  Menge  Initialspreng- 
stoff,  je  nachdem  seine  Detonationswellen  frei  auslaufen  oder 
sich  entgegenkommen,  verschieden  starke  Initialwirkungen  her- 
vorgerufen  werden  konnen.  Nach  der  bisherigen  Anschauung 
musste  man  insbesondere  annehmen,  dass  zwei  in  eine  Spreng- 
stoffmasse  eingefiihrte  Detonationsztindschnure  mit  frei  aus- 
laufenden  Detonationswellen  mindestens  die  gleiche  initiierende 
Wirkung  ausiiben  wiirden,  wie  eine  Zlindschnur  allein,  in  der  die 
Detonationswellen  einander  entgegen  laufen.  In  Wahrheit  ist  die 
Wirkung  im  letzteren  Falle  erhablich  starker;  der  Unterschied 


iv]  Congress  of  Applied  Chemistry  21 

gegeniiber  den  bisherigen  Initialwirkungen  1st  ein  unter  Umstanden 
sehr  bedeutender.  Als  50  g  Sprenggelatine  in  einer  grossen  Blei- 
kugel  detoniert  wurden,  betrug  der  entstandene  Hohlraum  bei 
Ziindung  mit  Knallquecksilbersprengkapsel  Nr.  8  2700  ccm,  bei 
Ziindung  mit  aufeinanderstossenden  Detonationswellen  3300 
ccm,  also  um  22  Prozent  mehr.  Bei  Sprengversuchen  mit  Gra- 
naten,  die  eine  Sprengladung  von  250  g  gegossenem  Trinitrotoluol 
besassen,  wurden  durch  Initiierung  mit  zwei  einfachen  Deto- 
nationswellen insgesamt  50  wirksame  Sprengstiicke  gezahlt,  bei 
Initiierung  mit  zwei  aufeinanderstossenden  Detonationswellen 
aber  206  wirksame  Sprengstiicke.  Bei  Vergleichsversuchen, 
angestellt  mit  diinnen  Detonationsziindschniiren  unter  sonst 
gleichen  Bedingungen,  tibertrug  die  einfache  Detonationswelle 
die  Detonation  noch  nicht  durch  einen  Luftraum  von  0,5  mm; 
die  Kumulationswelle,  wie  man  den  Treffpunkt  zweier  aus  ent- 
gegengesetzter  Richtung  zusammenstossenden  Detonationswellen 
nennen  konnte,  aber  auf  mehr  als  2  mm  Entfernung. 

Es  scheint  moglich  zu  sein,  die  Wirkung  der  Kumulationswelle 
noch  weiter  zu  verstarken,  indem  man  das  zugrunde  liegende 
Prinzip  wiederholt  zur  Anwendung  bringt,  z.  B.  indem  man 
jeden  Arm  einer  U-formig  gestalteten  Patrone  durch  Kumulations- 
zundung  initiiert  und  die  in  dieser  Ziindpatrone  entstandene 
sekundare  Kumulationswelle  ihrerseits  zur  Initiierung  der  eigent- 
lichen  Sprengladung  verwendet.  Ob  auch  eine  Schwachung  der 
Kumulationswelle  in  dem  Sinne  stattfinden  konne,  dass  sich 
entgegenkommende  Detonationswellen  von  ungleicher  Phase 
gegenseitig  aufheben,  mag  dahingestellt  bleiben. 

Die  zur  praktischen  Anwendung  dieser  neuen  Initialziindung 
erforderliche  Anordnung  besteht  also  darin,  die  Sprengladung  in 
unmittelbare  Beriihrung  mit  dem  Orte  des  Zusammenprallens 
der  Detonationswellen  zu  bringen,  entweder  in  der  Art,  dass  die 
Sprengladung  jene  Stelle  in  sich  aufnimmt,  oder  so,  dass  jene 
Stelle  aussen  an  der  Sprengladung  anliegt. 

Es  ist  nach  diesem  Verfahren  moglich,  nicht  mur  die  Wirkung 
der  bekannten  Sprengstoffe  sehr  zu  verstarken,  sondern  auch 
solche  Sprengstoffe  und  Sprengstoffmischungen  zur  vollkommenen 
Detonation  zu  bringen,  welche  mit  den  bisherigen  Hulfsmitteln 
unvollstandi  g  detonieren  und  deshalb  fur  die  Technik  nicht 


22  Original  Communications:  Eighth  International 

zweckmassig  ausgenutzt  werden  konnten.  Sobald  das  neue 
Verfahren  soweit  ausgebildet  sein  wird,  dass  es  eine  unmittelbare 
Verwertung  erlaubt,  diirfte  es  von  Bedeutung  sein  sowohl  fur 
die  Artillerie,  fiir  Granaten,  Minen,  Torpedos,  als  auch  fiir  den 
Bergbau,  insbesondere  durch  Anwendung  von  unempfindlicheren 
Sprengstoffmischungen  und  fiir  die  Sprengtechnik  im  allgemeinen. 
Die  neue  Initialziindung  zur  Detonierung  von  Sprengstoffen 
ist  der  Centralstelle  fiir  wissenschaftlich-technische  Untersuch- 
ungen  in  Neubabelsberg  patentrechtlich  geschiitzt;  in  Deutschland 
z.  B.  durch  D.  R.  P.  Nr.  245087. 


Abstract 

THE  MISUSE  OF  EXPLOSIVES.     ITS  EXTENT   AND 
PREVENTION 

BY  THOMAS  M.  CHATARD 
Washington,  D.  C. 

Noting  the  statement  of  a  Portuguese  revolutionist  that  ''bombs 
are  cheaper  and,  in  the  hands  of  untrained  people,  more  effective 
than  other  weapons,"  this  paper  gives  the  results  of  a  tabulation 
of  772  instances  of  the  misuse  of  high  explosives  from  1903  to 
1911,  inclusive.  In  the  United  States  alone,  there  were  213 
explosions  due  to  labor  troubles  and  238  Black  Hand  outrages, 
while  139  occurrences  can  only  be  ascribed  to  absolute  lawlessness. 

This  lawlessness  is  especially  dwelt  upon  in  the  discussion  of 
the  results,  which  is  confined  to  conditions  existing  in  the  United 
States.  These  conditions  and  the  legal  difficulties  attending  any 
legislation  against  and  prosecution  of  such  offenses,  in  this  country, 
are  particularly  considered  since  any  proposed  remedy  must  be 
in  conformity  with  them,  if  any  practical  benefit  is  to  be  expected, 
and  the  difficulties  are  greater  here  than  abroad. 

The  importance  of  the  co-operation  of  the  Sections  of  Explosives 
and  of  Law,  of  this  International  Congress,  in  securing  adequate 
and  satisfactory  legislation  and  legal  practice  to  this  end  is  pointed 
out  and  the  character  and  scope  of  this  co-operation  is  indicated, 
while  the  need  of  such  action  is  evidenced  by  the  extent  of  this 
abuse  and  by  the  statements  of  prominent  radical-socialistic 
leaders. 

The  fundamental  principle  of  the  suggested  legislation  is  that 
"the  unlicensed  possession  of  any  high  explosive  shall  be  a  punish- 
able offense,  without  reference  to  the  intentions  of  the  trans- 
gressor" and  instances  of  such  laws  are  given.  A  plan  of  a  licens- 
ing system  is  outlined  with  examples  of  its  practical  working. 
"It  is  prevention,  not  punishment,  that  is  to  be  sought  for"  and 
this  can  best  be  obtained  by  enacting  reasonable  laws,  satis- 
factory to  legitimate  business,  and  then  rigidly  enforcing  them. 

23 


SUR  L'INFLAMMABILITE   DE   L' ACETYLENE 
MELANGE  DE  30%   D'AIR   ENVIRON 

PAR  M.  MARCEL  DELEPINE 

Agrege  pres  VEcole  superieure  de  Pharmacie  de  Paris, 
Paris,  France 

On  salt  que  1 'acetylene  pur  ne  brule  avec  tout  son  eclat  dans 
1'air  que  s'il  s'echappe  des  bees  avec  une  pression  assez  consid- 
erable; si  la  pression  est  insuffisante,  le  brassage  de  1'air  avec  le 
gaz  est  imparfait,  la  flamme  est  fuligineuse  et  I'orifice  du  bee 
s'encrasse.  Aussi  a-t-on  du  remedier  a  ces  inconve"nients  en 
utilisant  des  bruleurs-melangeurs  d'air. 

On  arrive  egalement  a  de  bons  resultats  en  brulant  non  pas 
le  gaz  pur,  mais  le  gaz  prealablement  melange  d'une  certaine 
quantite  d'air.  L 'experience  montre  qu'un  melange  contenant 
aux  environs  de  30%  d'air  et  70%  d 'acetylene,  brule  avec  un 
eclat  plus  grand  encore  que  l'ace*tylene  pur,  tout  en  n'exigeant 
qu'une  pression  de  quelques  centimetres  d'eau.  Pour  un  meme 
eclairage,  la  depense  est  un  peu  moindre  et  les  canalisations  du 
gaz  de  houille  ordinaire  suffisent.  On  arrive  tres  simplement  a 
re*aliser  des  melanges  d'une  composition  determinee  en  divisant 
le  tambour  d'un  compteur  a  gaz  en  deux  compartiments  soli- 
daires  de  capacites  inegales:  1'un  des  compartiments  debite  de 
1'acetylene  qui  le  fait  tourner  par  sa  pression,  1'autre  debite  de 
1'air;  les  deux  gaz  se  melangent  ensuite  dans  une  chambre  unique 
avant  de  se  rendre  aux  canalisations.  C'est  d'un  appareil  sem- 
blable,  le  me*langeur-doseur  OVING  que  je  me  suis  servi. 

Etant  donnee  la  grande  puissance  explosive  de  l'ace*tyl£ne  et 
de  ses  melanges  avec  1'air,  il  etait  bon  de  proce*der  a  quelques 
experiences  sur  1'inflammabilit^  des  melanges  fournis  par  les 
appareils  en  question  et  je  crois  utile  de  les  communiquer  a  titre 
de  contribution  a  1'etude  des  melanges  combustibles. 

Get  examen  nitrite  d'autant  plus  de  nous  arreter  qu'il  y  a 
quelque  indecision  sur  les  limites  d  'inflammabilite  des  melanges 
d'oxygene  et  d'air.  LE  CHATELIER  (C.  R.  Ac.  Sc.,  t.  121,  p. 
1144;  1895)  donne  les  limites  infe"rieure  et  supe*rieure,  2,  8  et  65% 
d 'acetylene;  CLOWES  (Report  of  the  Britisch  Association,  1896, 

25 


26  Original  Communications:  Eighth  International        [VOL. 

p.  746)  donne  3  a  82%  pour  1'inflammation  par  flamme;  GERDES 
(Chem.  und  chem-techn.  Vortrdge,  t.  4,  p.  249;  1899)  indique  2,  5 
a  80%  pour  un  melange  de  90  litres  soumis  a  1  'influence  de  Tetin- 
celle  electrique.  LE  CHATELIER  a,  en  outre,  fait  observer  que 
le  chiffre  de  65%  est  un  maximum  constate*  dans  une  masse  de 
grand  volume;  les  limites  se  resserrent  notallement  si  Ton  opere 
dans  des  tubes  e"troits. 

Dans  les  experiences  qui  suivent,  le  melange  fut  analyse"  chaque 
fois.  Pour  cela  on  remplissait  les  appareils  destines  aux  essais 
par  un  balayage  suffisant  et  re*coltait  a  leur  extremite*  meme  une 
fraction  destinee  a  1'analyse.  Celle-ci  e*tait  bien  simple:  il  suffi- 
sait,  en  effet,  de  mesurer  1  'absorption  produite  dans  le  melange 
par  le  chlorure  cuivreux  ammoniacal  qui  s'empare  a  la  fois  de 
1  'ac&tylene  et  de  I'oxyg&ne,  en  ne  laissant  que  1  'azote  et  ses  com- 
pagnons.  J'ai  d'ailleurs  ve*rifie  que  Ton  arrivait  aux  memes 
re*sultats  que  si  1'on  absorbait  successivement  I'oxyg&ne  par  le 
pyrogallate  et  1  'acetylene  par  le  reactif  cuivreux.  Voici  deux  de 
ces  analyses  comparatives  d'un  meme  e*chantillon  : 

I.   Gaz  du  me*langeur  .  .  .  .............  29,2  c.  cub. 

Res  apres  absorption  de  C2H2  et  O2    6,1  c.  cub.  =  azote 

D'ou,  air=^i-  =  7,7  c.  cub.    soit  ........  26,4% 

0,79 

II.  Gaz  depouille"  de  O2  .  V  ............  29,2  c.  cub. 

Reste  apres  absorption  de  C2H2  ......  6,5  c.  cub.  =  azote. 

f  acetylene  ..........  22,7    c.  cub. 

8,22,  soit  26,6%. 


D'ou>  \  air  =  M- 
I          0,79 


Total  30,92 

I.  Etincelk  d'  induction.  —  Une  premiere  s^rie  d  'experiences 
a  montre  que  des  melanges  contenant  de  25,4  a  31%  d'air  ne 
s  'enflammaient  pas  lorsqu'on  les  soumettait  a  des  exces  de  pres- 
sion  sur  la  pression  atmospherique  allant  de  3,5  a  39  centimetres 
de  mercure  (1,5  atm.  de  pression  totale)  et  qu'on  y  faisait  passer 
des  e*tincelles  d  'induction  de  2  millimetres  de  longueur  environ. 
II  se  faisait  tout  au  plus  un  petit  de"p6t  de  charbon  sur  les  poles. 


iv]  Congress  of  Applied  Chemistry  27 

II.  Fit  de  fer  incandescent.  —  Une  deuxi£me  se*rie  a  e*te*  faite 
en  portant  au  bon  rouge,  au  moyen  cTun   courant    electrique, 
un  fil  de  fer  de  2  centimetres  de  long  place*  au  sein  du  melange 
gazeux  renferme*  dans  une  ampoule  ovoide  d'un  litre;  un  bouchon 
de  caoutchouc  moyennement  serre*  dans  le  goulot  laissait  passer 
les  conducteurs  et  servait  en  meme  temps  a  clore  1'ampoule. 

Aucun  des  melanges  contenant  de  25  a  31%  d'air,  examines 
sous  ses  pressions  allant  de  0,3  a  15  centimetres  de  mercure  m'a 
donne*  d 'inflammation.  On  a  observe*  seulement  un  de*pot  de 
charbon  lanugineux  sur  le  fil  devenu  cassant. 

Toutefois,  une  experience  faite  avec  un  courant  suffisant  pour 
fondre  le  fil  et  sous  la  surpression  de  3  cm.  5,  a  couse*  une  inflam- 
mation qui  a  chasse*  le  bouchon  de  1'appareil,  avec  production 
abondante  de  noir  de  fume*e. 

III.  Fil  de  platine  incandescent.  —  On  a  remplace*  le  fil  de  fer 
par  du  fil  de  platine,  en  conservant  le  m£me  dispositif. 

Dans  un  premier  groupe  d 'experiences  avec  un  fil  de  0,1  mil- 
limetre de  diam  tre  et  10  millimetres  de  longueur,  sous  des  exc£s 
de  pression  variant  de  0,5  a  11,3  centimetres  de  mercure  et  une 
teneur  en  air  de  28%,  on  n'a  rien  observe*.  On  a  m6me  pu  dans 
un  cas  fondre  le  fil  de  platine  sans  provoquer  d 'inflammation. 

Par  centre,  dans  un  second  groupe  d 'experiences  avec  un  fil 
de  0,2  millimetre  de  diametre  et  20  a  30  millimetres  de  longueur, 
des  melanges  contenant  de  26,5  a  32,6%  d'air  ont  toujours  ete 
enflammes,  m&ne  sous  la  pression  tres  reduite  de  quelques  mil- 
limetres de  mercure  en  sus  de  la  pression  ambiante. 

Ce  m&me  fil  place*,  non  plus  dans  1'ampoule  d'un  litre,  mais 
dans  1'axe  d'un  tube  de  plomb  de  20  millimetres  de  diam&tre 
et  de  1,40  metre  de  long  (avec  ou  sans  garniture  isolante  de  verre) 
n'a  laisse*  apparaitre  que  des  traces  de  charbon  dans  le  voisinage 
du  fil  de  platine,  malgre  que  1 'incandescence  eut  ete*  maintenue 
plus  d'une  minute  et  eut  meme  e*te  pousse*e  jusqu'a  la  fusion  du 
fil;  ce  qui  montrait  que  la  combustion,  fort  restreinte,  s'e*tait 
limite*e. 

IV.  Fulminate  de  mercure.  —  Une    quatrieme    se*rie    d 'expedi- 
ences a  enfin  e*te*  exe*cute*e  en  faisant  detoner  un  peu  de  fulminate 
de  mercure  au  sein  de  1'ampoule  d'un  litre.     La  detonation  du 


28  Original  Communications:  Eighth  International        [VOL. 

fulminate  etait  provoquee  par  le  contact   d'un  fil  chauffe  juste 
assez  au  moyen  d'un  courant  electrique. 

Pour  un  poids  de  fulminate  de  0,005  gr.  detonant  dans  des 
melanges  a  29%  sous  des  exces  de  pression  allant  de  1  a  4  centi- 
metres de  mercure,  on  n'a  pas  eu  d 'inflammation. 

Pour  un  poids  double,  soit  0,01  gr.,  on  a  eu  les  re*sultats  suivants: 

Air  %  du  melange  Pression  en                                Resultat 

centim.  de  Hg 

25,4  1  Rien. 

25,4  . 4  Rien. 

28,0  1  Rien. 

28,0  1  Inflammation. 

28,0  4  Inflammation. 

23,0  9  Rien. 

23,0  15  Explosion  vive. 

29,0  1  Inflammation. 

CONCLUSIONS 

II  ressort  nettement  des  experiences  que  de  courtes  etincelles 
sont  sans  effet,  meme  pour  des  compressions  d'une  atmosphere 
et  demie.  Le  fil  de  fer  est  egalement  peu  efncace;  cependant  a 
sa  temperature  de  fusion,  il  a  provoque  une  inflammation. 

Les  experiences  avec  les  fils  de  platine  montrent  que  ce  metal 
est  plus  actif  que  le  fer,  sans  doute  parce  qu'on  peut  le  chauffer 
plus  haut  sans  le  fondre.  Toutefois,  les  result ats  negatifs  obtenus 
avec  le  fil  de  0,1  millimetre,  meme  a  la  temperature  de  fusion, 
montrent  que  la  temperature  en  un  point  n'est  pas  le  seul  facteur 
a  considerer :  1  'etendue  de  la  surface  chaude  doit  entrer  en  ligne 
de  compte  en  permettant  de  decomposer  dans  le  voisinage  du 
fil  une  plus  grande  quantite*  d 'acetylene  dont  1'hydrogene  a  un 
moment  donne*  devient  assez  abondant  pour  former  avec  1'air 
un  melange  explosif,  meilleur  transmetteur  d 'inflammation  (ou 
d 'explosion)  que  le  fil  chaud.  C'est  pourquoi  un  fil  plus  gros  et 
plus  long  a  egalite  de  temperature  est  plus  efficace.  L 'experience 
en  tube  de  plomb  qui  ne  permet  sans  doute  pas  le  melange  rapide 
de  1'hydrogene  avec  1'oxygene  conduit  naturellement  a  un  re- 
sultat  negatif.  Cette  maniere  d'etre  du  melange,  suivant  qu'il 
est  dans  un  recipient  tubulaire  ou  un  recipient  globoide,  est  a 
rapprocher  de  celle  qui  a  ete  constatee  par  MM.  BERTHELOT 


iv]  Congress  of  Applied  Chemistry  29 

et  VIEILLE  (Ann.  chim.  et  phys.  [7],  t.  16,  p.  24;  1899)  pour  la 
decomposition  de  1 'acetylene  pur.  Alors  que  le  fil  rougi  ou  Pamorce 
de*truisent  1 'acetylene  dans  des  vases  de  grande  capacite*,  ils  ne 
produisent  qu'une  faible  decomposition  locale  dans  des  tubes 
e*troits,  les  conditions  de  pression  etant  elgales  d'ailleurs. 

Les  experiences  faites  avec  le  fulminate  montrent  que  cet  agent 
est  tres  actif.  Son  influence  depend  de  la  dose  puisque  les  explo- 
sions de  0,005  gr.  n'ont  produit  aucun  effet,  sous  une  surpression 
de  1  a  4  centimetres  de  mercure  et  une  teneur  de  29%  d'air,  alors 
que  ce  meme  melange  et  meme  celui  a  28%  s'enflamme  sous  une 
pression  de  1  centimetre,  s'il  y  a  0,01  gr.  de  fulminate.  Pour 
une  meme  dose,  la  composition  a  une  influence  notable;  avec 
23%  d'air,  il  faut  depasser  9  centimetres  de  mercure  pour  avoir 
rinflammation,  tandis  qu'avec  28%,  elle  a  lieu  pour  4  centimetres 
et  meme  1  centimetre;  il  en  est  de  meme  pour  le  melange  a  29%. 
L 'experience  a  23%  d'air  montre  aussi  que  la  pression  est  un  fac- 
teur  efficace  qui  peut  compenser  le  deficit  en  air. 

Les  inflammation  generalise*es  qui  ont  produit  la  chasse  du 
bouchon  seraient,  a  mon  avis,  dues  a  trois  phenomenes  successifs: 
decomposition  au  contact  des  fils  ou  des  amorces  d'un  volume 
determine  d 'acetylene  dans  un  premier  temps  et  remplacement 
du  gaz  detruit  par  son  volume  d'hydrogene;  combinaison  ex- 
plosive du  melange  d'hydrogene  et  d'air  qui  s'est  ainsi  substitue 
au  melange  primitif,  dans  un  deuxieme  temps;  le  melange  nouveau 
aurait  en  effet  la  composition :  18%  (2H2  +  O2)  +  24%  azote  +  54% 
de  C2H2  ou  de  H2,  en  moyenne;  si  ce  melange  est  forme  en  quantite 
suffisante  dans  un  temps  tres  court,  il  est  alors  capable  dans  un 
troisieme  temps,  en  raison  de  la  grande  vitesse  de  son  onde  ex- 
plosive de  propager  1 'inflammation  dans  le  reste  du  melange  non 
decompose  ou  d'y  produire  une  decomposition  notable  de  1  'acety- 
lene. La  seule  veritable  explosion  qui  ait  e"te  remarquee  est  celle 
qu  avait  provoquee  la  charge  de  0,01  gr.  de  fulminate  sous  la 
sur  pression  de  15  centimetres  de  mercure. 

Toutes  ces  hypotheses  se  coordonnent  avec  la  constatation 
d'une  plus  facile  inflammation  si  1'on  augmente  Pe*nergie  des 
processus  primordiaux  de  la  decomposition,  ce  qui  peut  se  re*ali- 
ser,  soit  en  augmentant  le  volume  de  la  zone  atteninte,  par  1'em- 
ploi  d'un  gros  fil  ou  d'une  plus  grosse  amorce,  soit  en  augmentant 
la  pression. 


TETRANITROANILINE,  A  NEW  HIGH  EXPLOSIVE 

BY  DR.   BERNHARD   FLURSCHEIM 
Rushmoor  Fleet,  Hampshire,   England 

A  compound  which  would  combine  the  stability  of  an  aromatic 
nitro-derivative  with  the  explosive  power  of  an  aliphatic  nitro- 
ether  has  long  been  an  object  of  research  work  on  explosives. 

The  nearest  approach  to  this  combination  of  properties  hither- 
to realised  seems  to  have  been  tetryl  (tetranitromethylaniline) . 
Partly  owing,  however,  to  its  expensive  manufacture,  and  partly 
to  its  small  resistance  to  heat  and  mechanical  influences,  due 
undoubtedly  to  the  non-aromatic  linking  of  one  of  the  nitro- 
groups,  the  use  of  tetryl  seems  practically  to  have  been  confined 
to  detonators. 

It  may  therefore  be  of  interest  to  record  some  of  the  prop- 
erties of  an  entirely  aromatic  compound  of  quite  recent  discovery, 
"tetranitroaniline,"  as  this  has  been  found  to  combine  perfect 
aromatic  stability  with  quite  exceptional  "brisance,"  while  also 
complying  with  other  industrial  postulates,  such  as  high  specific 
gravity  and  economic  manufacture. 

Tetranitroaniline  (abbreviated  T.  N.  A.)  is  obtained  by  various 
methods  which  will  be  published  shortly.  The  commercial 
method  consists  in  treating  meta-nitroani  ine  with  a  mixture  of 
sulphuric  and  nitric  acids,  whereupon  the  tetranitroaniline  sep- 
arates from  the  undiluted  acid  in  pure  crystals  which  are  filtered 
off  and  washed  with  water,  the  waste  acid  serving  for  the  manu- 
facture of  nitric  acid.  The  meta-nitroaniline  in  its  turn  is  obtained 
by  another  new  process  whereby  commercial  dinitrobenzol  is 
reduced  by  means  of  sodiumbisulphide  and  water,  the  meta- 
nitroaniline  thus  produced  being  suitable  for  nitration  without 
previous  purification,  and  the  sodiumbisulphide  used  being  re- 
covered in  the  shape  of  sodiumhyposdphite.  In  this  way,  com- 
mercial dini  robenzol  yields  almost  its  own  weight  of  pure  tet- 
ranitroaniline. 


31 


32  Original  Communications:  Eighth  International        [VOL. 


T.  N.  A.  has  the  formula  ^,~ 


NH2 

and  conta'ns  25.6%  of  nitrogen  and  46.9%  of  oxygen.  It  is  a 
yellow  crystalline  compound.  Its  absolute  specific  gravity  is 
1.85.  It  melts  with  decomposition,  but  without  explosion,  at 
between  208°  and  215°  C.  according  to  the  rate  of  heating.  One 
part  is  soluble  in  about  6  parts  of  acetone.  It  can  be  re-crystal- 
lised from  a  number  of  solvents,  notably  from  xylene  and  from 
liquid  aromatic  nitro-compounds.  It  is  not  attacked  by  cold 
water,  in  which  it  is  insoluble.  By  heating  it  with  water  it  is 
slowly  transformed  into  trinitroaminophenol,  a  derivative  of 
picric  acid  T.  N.  A.  has  neither  acid,  nor  basic  properties.  It 
can  be  melted  with  trinitrotoluol,  dinitrobenzol  and  other  nitro- 
compounds,  no  decomposition  occurring  even  at  150°  C.  It 
gives  Abel  tests  of  over  an  hour.  On  a  lighted  piece  of  paper 
it  burns  gradually,  without  explosion.  When  spread  on  wood 
or  stone  and  lighted,  the  flame  does  not  spread.  Under  the  falling 
hammer  it  detonates  with  5  kilograms  at  35  cm.  (tetryl  at  22  cm.). 
When  detonated  by  a  primer,  it  gives  no  residue  or  smoke.  Its 
explosive  power,  as  measured  in  a  lead  block,  is  greater  than 
that  of  any  other  solid  compound,  but  is  inferior  to  that  of  nitro- 
glycerine. The  enlargement  of  the  cavity  by  T.  N.  A.  is,  for 
instance,  40  to  50%  greater  than  for  trinitrotoluol  and  picric 
acid  and  20%  greater  than  for  tetryl  and  gun-cotton. 

T.  N.  A.  can  be  compressed  at  high  pressures,  either  alone 
with  nitrates  in  suitable  proportions,  without  losing  its  capacity 
of  being  easily  detonated,  _as  is  the  case  with  other  aromatic  nitro- 
compounds.  This  was,  or  instance,  ascertained  for  a  mixture 
of  35%  T.  N.  A.  with  65%  Ammoniumnitrate,  compressed  to 
a  specific  gravity  of  1.6;  also  for  a  mixture  of  50%  T.  N.  A., 
40%  Bariumnitrate  and  10%  Potassiumnitrate,  compressed  at 
145  atmospheres  to  a  density  of  1.8  (without  allowing  for  the 
central  cavity  of  the  cartridge).  The  latter  mixture  was  compared 
with  an  analogous  composition  made  from  gun-cotton  and  ni- 


iv]  Congress  of  Applied  Chemistry  33 

trates  (with  which  a  density  of  1.275  was  obtained  on  compression), 
cartridges  of  both  being  fired  by  means  of  a  Nr.  6  detonator  on 
hardened  iron  bars,  when  a  considerably  deeper  groove  was 
produced  by  the  T.  N.  A.  composition. 

In  detonators  T.  N.  A.  produces  strong  effects  with  a  small 
amount  of  fulminate  as  primer.  With  T.  N.  A.  in  propelling 
charges,  in  charges  for  projectiles  and  in  detonating  fuses,  some 
interesting  results  are  being  obtained. 

The  following  calorimetric  tests  were  carried  out  by  Mr.  W. 
Macnab,  F.  I.  C.: 

Results  of  firing  Tetranitroaniline  and  some  mixtures  in  large 
calorimetric  bomb  from  which  the  air  had  been  pumped  out. 

TETRANITROANILINE 

cc.  perm.         Composition  of  perm,  gas 
cals  per  gr.  gas  per 

Charge    Case     (water  liq.)     gram        CO2      CO       CH4         H  N 

55  grm.  glass       1017        827      21.5     38.3     1.2        15.1     23.9 
100  grm.  glass       1018  25.0     33.1     0.6        18.5      22.8 

Mixtures  12  3 

Ammonium  nitrate  86  81  87 

Trinitrotoluene  8 

Tetranitroaniline  13 

"Tetra"  &  Dinitrobenzene  7 

Black  charcoal  66  6 

100  100  100 


cals.  per  grm.  (water  liq.)  1131  1160  1154 

cals.  per  grm.  (gaseous)  903  933  913 

cc.  perm,  gas  per  gram  411  443  416 

COMPOSITION   OP   GASES 

C02  26.3  37.7  26.5 

CO  3.3  3.5  4.1 

H  8.5  4.1  8.5 

N  61.9  54.7  60.9 


100.0  100.0  100.0 


No.  8  Fulminate  detonators  used. 


AUSZUG  AUS  DEM  VORTRAGE:  DIE  INTERNATIONALE 

REGELUNG  DER  VORSCHRIFTEN  UBER  DEN 

POST-,  EISENBAHN-  UND  SEETRANSPORT 

EXPLOSIVER,   LEICHT  BRENNBARER, 

AETZENDER,  ETC.,  PRODUKTE 

VON  C.   GOPNER 
Hamburg,   Germany 

I.  Beziiglich  des  internationalen  Postversands  wird  dem  Wun- 
sche  Ausdruck  gegeben,  den  schon  von  Herrn  Dr.  C.  A.  von  Martius 
auf  dem  6.  internationalen  Kongresse  zu  Rom  vorgeschlagenen 
Wortlaut:  "  dass  eine  genauere  Definition  oder  speziellere  Auf- 
"  zeichnung  der  als  explosiv,  leicht  entziindlich,  von  der  Befor- 
' '  derung  auszuschliessenden  Gegenstande  durch  Internationale 
"  Uebereinkunft  gegeben  werde." 

zu  wiederholen  und  diessen  Wunsch  in  Form  einer  Resolution 
zum  Ausdruck  zu  bringen. 
II.  Eisenbahnversand  gefahrlicher  giiter. 

Es  wird  die  lange  Frist,  welche  die  von  den  beauftragten  Del- 
egierten  der  Staaten,  welche  das  internationale  Uebereinkommen 
iiber  den  Eisenbahnfrachtverkehr  abgeschlossen  haben,  gefassten 
Beschliisse  bis  zu  ihrer  Ratifizierung  und  in  Kraftsetzung  ge- 
brauchen,  bemangelt.  Wenn  diese  bis  jetzt  2-3  Jahre  beansprucht 
haben,  so  wird  es  nach  dem  neuen  Wortlaute  des  Uebereinkommens 
7-8  Jahre  dauern,  bis  Aenderungen  und  Erganzungen,  namentlich 
der  Vorschriften  tiber  die  bedingungsweise  zum  Transport  auf 
Eisenbahnen  zugelassenen  Gegenstande,  Giiltigkeit  erlangen. 

Es  wird  deshalb  vorgeschlagen,  derartige  Sachen  sofort  nach 
ihrem  Eingange  zu  beraten,  dariiber  Beschluss  zu  fassen  und 
schnellstens  zur  Giiltigkeit  zu  bringen. 

Es  wird  als  wtinschenswert  bezeichnet,  dass  nicht  nur  alle 
europaischen  Staaten,  sondern  auch  die  der  tibrigen  Continente 
dem  internationalen  Uebereinkommen  fur  den  Eisenbahnfracht- 
verkehr beitreten. 

35 


36  Original  Communications:  Eighth  International 

Es  wird  vorgeschlagen,  die  Vorschriften  aller  Staaten  iiber 
den  Frachtverkehr,  resp.  liber  die  bedingungsweise  zum  Eisen- 
bahnversand  zugelassenen  Gegenstande,  zu  sammeln,  das  Ver- 
zeichnis  derselben  zu  erganzen,  genaue  Vorschriften  iiber  die  in 
einem  Versandsttick  zusammen  zu  packenden  Gegenstande  zu 
schaffen,  und  ein  Verzeichnis  der  Giiter,  welche  zum  Eilgutverkehr 
zuzulassen  sind,  anzufertigen. 
III.  Beforderung  gefahrlicher  Gtiter  mit  Kauffahrteischiffen. 

Am  1.  Juni  dieses  Jahres  ist  von  am  Seeverkehr  beteiligten 
deutschen  Staaten  eine  Verordnung  in  Kraft  getreten,  welche 
diese  Sache  in  systematischer  Weise  regelt  und  sich  im  Grossen 
und  Ganzen  an  die  fur  den  Eisenbahnverkehr  in  Deutschland 
geltenden  Bestimmungen  anschliesst. 

Es  wird  ein  Antrag  gestellt,  die  Regierung  der  Vereinigten 
Staaten  zu  veranlassen: 

1.  zu  untersuchen,  ob  es  im  Interesse  von   Handel,  Industrie 
und  Schifffahrt  liegt,  einheitliche  Vorschriften  fiir  den  Trans- 
port von  gefahrlichen  Gtitern  mit  Kauffahrteischiffen  zu  bes- 
itzen,  und 

2.  im  Falle  die  Regierung  der  Vereinigten  Staaten  diese  Meinung 
teilt,  eine  Konferenz  der  an  der  Frage  interessierten  Seestaaten 
zu  berufen,  mit  dem  Auftrage,  solche  Vorschriften  zu  entwerfen 
und  zu  ratifizieren. 


THE  PREPARATION,  CRYSTALLINE  STRUCTURE,  AND 

PHYSICAL  PROPERTIES  OF  THE  TWO  FORMS  OF 

SOLID  NITROGLYCERINE 

BY  HAROLD  HIBBERT 

Wilmington,  Delaware 


INTRODUCTION 

On  account  of  the  extended  use  to  which  nitroglycerine  is  put 
in  the  explosives  industry,  a  knowledge  of  its  physical  properties 
is  of  great  importance,  and  this  is  especially  true  regarding  the 
"  solid  product,"  viz.,  frozen  nitroglycerine  explosives,  due  largely 
to  the  fact  that  nitroglycerine  may  often  be  supercooled  to  an 
extraordinary  degree  (  —  70°  C.)  without  showing  any  tendency  to 
solidify.  An  exact  determination  of  the  freezing-  and  melting- 
points  occasions  some  difficulty  so  that  the  value  of  these  constants 
as  determined  by  various  investigators  varies  considerably. 

In  the  patent  specification  of  Nobel  (U.  S.  patent  No.  57,  175, 
issued  August  14,  1866)  the  patentee  draws  attention  to  the  fact 
that  his  nitroglycerine  product  differs  from  that  previously  ob- 
tained by  Sobrero  in  that  it  can  be  readily  induced  to  crystallize 
at  a  comparatively  low  temperature,  viz.,  around  55°  F.  (equiva- 
lent to  12.8°  C.)  and  it  is  an  interesting  fact  that  though  this 
value  is  not  quoted  in  the  literature  on  the  subject  it  is  in  very 
close  agreement  with  that  obtained  in  recent  investigations,  the 
more  reliable  of  which  are  those  carried  out  by  Nauckhoff  and 
Kast. 

Nauckhoff  (Zeit.  angew.  Chem.  1905,  18,  pp.  11  and  53)  in  a 
very  interesting  paper  on  the  physical  properties  of  nitroglycerine 
found  the  melting-point  to  be  12-12.4°  C.  The  subject  was  taken 
up  later  by  Kast  (Zeit.  Schiess.  u.  Spreng.,  1906,  1,  p.  225)  who 
introduced  another  complication  by  his  claim  to  have  discovered 
that  solid  nitroglycerine  is  capable  of  existing  in  two  isomeric 
forms,  a  labile  isomeride  melting  at  2.8°  C.  and  a  stable  one  melt- 
ing at  13.5°  C.  In  a  later  paper  on  this  subject  by  Nauckhoff 

37 


38  Original  Communications:  Eighth  International        [VOL. 

(Zeit.  Schiess.  u.  Spreng.,  1911,  6,  p.  124)  in  which  a  description  of 
the  crystalline  structure  of  the  higher-melting  isomeride  is  given, 
this  author  confirms  the  above  value  for  the  melting-point  of  the 
stable  form  obtained  by  Kast,  viz.,  13.5°  C.,  but  differs  from  him  in 
finding  this  to  be  identical  with  the  value  for  the  freezing  point, 
coming  to  the  conclusion  that  the  value  (12-12.4°  C.)  obtained 
previously  was  due  to  the  nitroglycerine  used  by  him  not  having 
been  sufficiently  pure.  He  was  not  successful,  however,  in  pre- 
paring the  lower-melting  labile  isomeride. 

In  connection  with  another  investigation  in  which  frozen  nitro- 
glycerine was  desired,  the  author  prepared  a  sample  by  freezing 
a  mixture  of  nitroglycerine  and  wood-pulp  and  inoculating  from 
this,  whereby  a  product  was  obtained  which  melted  sharply  at 
1.0°  C.  and  was  apparently  identical  with  the  labile  isomeride  of 
Kast.  Since  Kast's  work  has  not  up  to  the  present  apparently 
been  generally  accepted,  and  especially  in  view  of  Nauckhoff's 
failure  to  duplicate  the  results,  it  was  deemed  advisable  to  repeat 
it  and  to  ascertain  whether  or  not  there  is,  in  reality,  a  second  iso- 
meric  labile  form  of  solid  nitroglycerine.  This  was  the  more 
necessary  since  apparently  the  labile  isomeride  had  been  obtained 
in  a  purely  accidental  manner  and  the  conditions  for  its  prepara- 
tion had  not  been  defined.  This  investigation  has  now  been 
carried  out  and  the  existence  of  the  second  solid  isomeride  defi- 
nitely established.  Furthermore,  its  physical  properties  (melting- 
and  freezing-point,  crystalline  structure,  etc.)  have  been  accu- 
rately determined  and  the  conditions  under  which  it  may  be  ob- 
tained settled  with  considerable  exactitude. 

According  to  our  measurements  the  labile  isomeride  freezes  at 
1.9°  C.  and  melts  at  2.0°  C.,  while  the  stable  form  freezes  at 
13.0°  C.  and  melts  at  13.2°  C.  Photomicrographs  of  both  forms 
have  also  been  obtained. 

EXPERIMENTAL   PART 

Conditions  under  which  the  Two  Forms  are  Obtained.  It  is  a  well- 
known  fact  that  various  dynamite  mixtures,  e.g.,  nitroglycerine, 
with  various  "  dopes,"  such  as  wood-pulp  with  sodium,  potassium 
or  ammonium  nitrate,  freeze  much  more  readily  than  does  nitro- 
glycerine alone,  and  as  it  is  customary  to  make  use  of  this  fact  in 


rv]  Congress  of  Applied  Chemistry  39 

preparing  solid  nitroglycerine,  a  mixture  of  nitroglycerine  with 
wood-pulp  was  taken,  cooled  to  —40°  C.,  stirred  with  a  glass  rod 
and  then  the  frozen  product  used  for  inoculating  another  sample  of 
the  same  nitroglycerine  also  cooled  to  the  same  temperature.    To 
the  author's  surprise,  and  as  already  stated,  the  crystalline  product 
so  obtained  was  found  to  melt  around  2°  C.,  and  thus  represented 
Kast's  labile  form.     This  experiment  was  repeated  many  times 
with  different  samples  of  nitroglycerine  recently  prepared  and  not 
previously  frozen,  and  always  with  the  same  result.    When,  how- 
ever, a  mixture  of  the  same  nitroglycerine  with  wood-pulp  and 
powdered  sodium  nitrate  was  taken,  then  on  carrying  out  the  same 
experiment  under  the  above  conditions,  (i.e.,  at  a  temperature 
of  —40°  C.)  the  product  crystallized  out  more  readily  but  was 
found  to  possess  a  melting-point  of  around  13°  C.,  i.e.,  it  was  the 
stable  modification.     This  experiment  has  also  been  repeated  very 
many  times  and  always  with  the  same  result,  viz.,  the  isolation  of 
the  higher-melting  isomeride,  although  its  formation  appeared  in 
a  large  number  of  cases  to  proceed  through  the  labile  form.     If  in 
the  above  experiments  a  sample  of  previously  frozen  nitroglycerine 
is  used  instead  of  one  which  has  not  been  previously  frozen,  the 
effect  of  mixing  with  wood-pulp  and  cooling  as  above  sometimes 
gives  the  labile  and  sometimes  the  stable  modification.     Even  in 
those  cases  where  the  labile  form  was  obtained  it  would  almost 
invariably  go  over  very  readily  (e.g.,  by  rubbing  vigorously  with  a 
glass  rod)  into  the  stable  isomeride.     The  addition  of  sodium 
nitrate  to  the  wood-pulp,  when  mixed  with  nitroglycerine  which 
has  been  previously  frozen,  invariably  gives  under  these  condi- 
tions the  stable  form.     Other  substances  may  be  substituted  for 
the  wood-pulp  in  the  preparation  of  the  labile  derivative,  e.g., 
powdered  glass-wool,  cotton-wool,  powdered  unglazed  porcelain, 
etc.,  the  most  efficient  of  all  being  powdered  glass-wool.    The 
following  methods  are  to  be  recommended  for  the  preparation  of 
the  two  isomerides: 

Preparation  of  the  Labile  Isomeride.  Unless  nitroglycerine 
which  has  not  been  previously  frozen,  and  preferably  recently 
made,  is  employed,  no  guarantee  can  be  giventh  at  the  labile  form 
will  separate  out  in  the  following  experiments,  but  with  this 
proviso  the  following  procedure  (as  shown  in  the  numerous  ex- 


4:0  Original  Communications:  Eighth  International        [VOL. 

periments  carried  out  by  us)  will  invariably  give  the  labile  isomer- 
ide.  As  thus  obtained  it  is  not  convertible  into  the  stable  form 
by  friction,  i.e.,  rubbing  with  a  glass  rod,  and  is  in  reality  a  com- 
paratively stable  product  below  0°  C.  provided  it  be  kept  free 
from  inoculation  with  the  higher-melting  isomeride.  The  nitro- 
glycerine (2  to  3  drops)  is  "absorbed"  in  powdered  glass-wool, 
cooled  to  —40°  C.,  and  stirred  with  a  glass  rod  at  this  temperature. 
A  trace  of  the  frozen  product  is  then  transferred  to  another  sample 
of  the  nitroglycerine  also  cooled  to  —40°  C.  and  the  sides  of  the 
tube  just  below  the  surface  of  the  liquid  rubbed  with  a  glass  rod; 
after  a  few  seconds  crystallization  to  the  labile  form  commences. 

Preparation  of  the  Stable  Isomeride.  The  procedure  corresponds 
exactly  with  that  indicated  above  for  the  labile  form  except  that 
a  mixture  of  wood-pulp  and  sodium  nitrate  is  employed  instead 
of  the  glass-wool,  and  preferably,  although  not  necessarily,  pre- 
viously frozen  nitroglycerine.  The  fact  that  Kast  succeeded  in 
obtaining  the  labile  isomeride  while  Nauckhoff  was  unsuccessful 
is  in  all  probability  due  to  the  accidental  circumstance  that  Kast 
used  a  sample  of  nitroglycerine  which  had  been  recently  made 
and  not  previously  frozen,  while  Nauckhoff  in  all  his  experiments 
may  have  worked  with  samples  which  had  been  previously  frozen 
or  the  manner  of  preparation  of  the  crystals  used  for  inoculation 
may  have  been  unsuitable. 

Method  of  Determining  the  Freezing-Point  of  the  Labile  Isomeride. 
The  apparatus  adopted  was  that  proposed  by  Kast  (Zeit.  Schiess. 
u.  Spreng.,  1906,7,  p.  225)  consisting,  as  shown  on  the  accompany- 
ing blueprint,  of  a  hard  glass  tube  (6"  by  f ")  surrounded 
by  an  outer  tube  to  serve  as  an  air-mantle  which  in  turn  is  sur- 
rounded by  a  freezing  mixture  of  ice  and  salt.  A  normal  ther- 
mometer, graduated  to  0.01°  C.  and  calibrated  at  the  Reichsen- 
stalt,  Berlin,  was  employed  for  taking  the  temperature,  the  stirring 
being  effected  by  means  of  a  platinum  stirrer  operated  mechanically 
in  the  manner  shown.  This  device,  due  to  the  flexibility  of  the 
stirrer,  obviates  the  danger  of  the  latter  becoming  imbedded  in 
the  frozen  material,  and  a  true  vertical  motion  is  maintained  by 
the  " sleeve  attachment"  in  which  a  brass  bar  slides,  to  which 
the  platinum  stirrer  is  attached.  In  our  experiments  the  tem- 
perature of  the  outer  bath  was  — 10°  to  - 14°  C.,  the  nitroglycerine 


PHOTOMICROGRAPHS  OF  THE  LABILE  ISOMERIDE  OF  NITROGLYCERINE. 


IV] 


Congress  of  Applied  Chemistry 


41 


being  cooled  to  —5°  to  —  6°C.  before  being  "seeded"  with  a 
small  crystal  of  either  isomeride  introduced  on  the  bulb  of  the 
thermometer.  The  stirrer  was  then  agitated  vigorously  and  the 
maximum  temperature  indicated  by  the  thermometer  was  taken 
as  the  freezing-point  of  the  sample.  The  time  elapsing  before 
this  temperature  was  reached  varied  only  slightly  (between  9  and 
12  minutes  for  both  forms)  with  the  different  samples.  Also  it 
made  no  appreciable  difference  in  the  value  obtained  for  the 
freezing-point  whether  the  product  was  supercooled  in  one  case  to 
—  4°  C.  and  in  another  case  to  —  8°  C.  In  all  experiments,  except 
in  the  one  or  two  special  cases  noted,  a  quantity  of  8  cc.  of  the 
sample  was  employed.  This  is  only  about  half  the  quantity  em- 
ployed by  Kast  but  a  comparative  experiment  using  double  this 
amount,  viz.,  16  cc.,  was  carried  out  and  gave  an  identical  value 
for  the  freezing-point,  as  indicated  below: 

EFFECT  OF  USING  DIFFERENT  QUANTITIES  OF  NITROGLYCERINE 
(Comparative  Experiments  with  Sample  No.  3) 


Quantity 
employed. 

Temperature 
to  which 
product 
was  cooled. 

Time  taken 
to  obtain 
maximum 
temperature. 

Labile  Isomeride. 

Freezing 
Point. 

Melting 
Point. 

8  CC. 
16  cc. 

°c. 

-5 
-5 

mins. 
10 
13 

°c. 

1.3 
1.3 

°c. 

1.7 
1.6 

Duplicate  tests  gave  identical  results. 

When  the  rate  of  stirring  was  decreased  so  that  the  length  of 
time  to  attain  the  maximum  temperature  increased  from  8  to  20 
minutes,  practically  no  difference  in  the  value  for  the  freezing- 
point  was  found.  Thus  in  one  case  (No.  3  sample)  when  rapid 
stirring  was  employed  the  freezing-point  was  found  to  be  1.3°  C. 
and  with  slow  stirring,  1.22°  C. 

Determination  of  the  Freezing-Point  of  the  Stable  Isomeride. 
Exactly  the  same  procedure  was  adopted,  except  that  the  nitro- 
glycerine was  first  cooled  to  5°  C.  to  6°  C.,  the  temperature  of  the 
outside  bath  being  maintained  at  0°  C. 


42 


Original  Communications:  Eighth  International        [VOL. 


Method  of  Determining  the  Melting-Point  of  the  Two  Isomerides. 
This  was  determined  by  replacing  the  outer  cooling  bath  used 
in  the  determination  of  the  freezing-point  by  water  at  a  tempera- 
ture of  15°  C.  and  then  stirring  until  the  bulb  of  the  thermometer 
just  became  visable.  This  point  corresponds,  as  pointed  out  by 
Kast  (loc.  cit.  p.  225) ,  to  the  point  above  which  the  thermometer 
commences  to  rise  very  rapidly.  The  melting-point  of  the  stable 
isomeride  was  determined  in  a  similar  manner  except  that  the 
temperature  of  the  outer  bath  was  raised  to  25°  to  30°  C.  The 
results  obtained,  together  with  the  description  of  the  samples  of 
nitroglycerine  employed,  including  the  analytical  data,  are  given 
in  Table  I. 

TABLE  I 


No. 

Description  of  Product 

%  Ni- 
trogen 

Labile 
Isomeride 

Stable 
Isomeride 

F.  P. 

M.  P. 

F.  P  . 

M.  P. 

1 

Product  was  made  by  nitrating  dynamite  glyc- 

°C. 

°C. 

oC, 

«C. 

erine  with  the  usual  nitrating  acid.1   The  nitro- 

0.9 

glycerine  obtained  was  thoroughly  washed  with 
dilute  carbonate  solution  and  then  with  water, 

18.47 

1.0 

1.4 

12.2 

12.6 

finally  dried  over  solid  potash  in  a  vacuum  des- 

18.47 

12.3 

12.7 

iccator;  it  possessed  a  light  straw  color. 

1.0 

2 

This  was  prepared  in  a  similar  manner  to  No.  1 

1.3 

1.7 

12.5 

12.9 

from  the  same  dynamite  glycerine.     Product 

18.50 

possessed  a  somewhat  darker  color  than  No.  1. 

1.3 

1.7 

12.5 

12.8 

3 

This  was  a  commercial  sample  of  nitroglycerine 

shipped  to  the  Experimental  Station  from  the 

1.1 

1.5 

not 

12.6 

Repauno  Works,  Gibbstown,  N.  J.,  in  acetone 

18.45 

deter- 

solution about  1905.     It  was  purified  as  above. 

1.0 

1.5 

mined 

12.6 

Product  possessed  a  bright  yellow  color. 

4 

This  sample  of  nitroglycerine  was  prepared  from 
C.P.  glycerine,  obtained  by  redistilling  the  C.P. 

trade  product  under  reduced  pressure  and  then 
nitrating  this  colorless  product  with  the  same 

18.50 
18.50 

1.0 
0.9 

1.4 
1.4 

12.2 
12.2 

12.5 
12.6 

acid  as  used  for  preparation  of  samples  No.  1 
and  No.  2.     It  was  purified  in  the  same  manner 

and  was  a  bright,  practically  colorless  liquid. 

25 

This  was  prepared  by  extracting  a  sample  of  40% 
"Atlas  Powder"   (a  straight  dynamite)  with 

18.32 

0.4 

1.2 

11.3 

12.4 

ether  and  evaporating    off    the    ether    under 

reduced    pressure    at    ordinary    temperature. 

18.36 

0.4 

1.2 

11.4 

12.5 

Product  was  a  dark  yellow  color. 

1This  nitrating  acid  had  the  following  composition: 

Actual  H2SO4 61.35< 

Actual  HNOs 32.K 

H(NO)SO< 

HsO 

2  This  sample  was  received  in  a  frozen  condition  and  was  thawed  out  prior  to  extracting  with 
ether. 


IV 


Congress  of  Applied  Chemistry 


43 


In  some  experiments  on  the  lowering  of  the  freezing-point  of 
nitroglycerine,  induced  by  various  additions,  carried  out  in  1904 
at  the  Eastern  Laboratory  of  the  E.  I.  duPont  deNemours 
Powder  Company,  at  Gibbstown,  N.  J.,  a  value  for  the  freezing- 
point  of  the  technical  product  equal  to  12.8°  C.  was  obtained, 
identical  with  the  value  given  by  Nobel  in  1866  (loc.  cit.). 

A  review  of  the  above  figures  shows  that  the  values  obtained 
in  the  present  investigation  are  approximately  1°  C.  lower  than 
those  obtained  by  Kast  and  Nauckhoff,  which  indicated  the  pos- 
sibility of  the  various  samples  either  containing  a  trace  of  moisture 
or  a  small  amount  of  some  impurity,  e.g.,  nitrated  polyglycerines. 
Accordingly,  samples  No.  2,  No.  3  and  No.  4  were  submitted  to  a 
process  of  fractional  recrystallization  by  cooling,  seeding  with  the 
stable  isomeride  and  after  partially  freezing,  pouring  off  the  mother 
liquor.  The  crystals  thus  obtained  were  then  melted,  and  the 
liquid  product  dried  for  a  week  over  anhydrous  barium  oxide  and 
phosphorus  pentoxide,  under  a  pressure  of  15  mm.  The  freezing- 
point  and  melting-point  of  each  sample  was  then  redetermined, 
when  the  following  values  were  obtained: 

TABLE  II 


Labile  Isomeride 

Stable  Isomeride 

Freezing 
Point 

Melting 
Point 

Freezing 
Point 

Melting 
Point 

Sample  No.  2 
Sample  No.  3 
Sample  No.  4 

1.7 
1.9 

not  det 

1.9 

2.0 
ermined 

12.8 
13.0 
12.4 

13.0 
13.2 
12.7 

Sample  No.  6 

1.8 

2.0 

12.9 

13.1 

A  second  fractional  recrystallization  did  not  result  in  any  altera- 
tion in  the  above  values.  It  will  be  observed  that  in  each  case 
there  is  a  marked  rise  in  the  freezing-  and  melting-points,  and 
that  those  obtained  with  samples  No.  2  and  No.  3  are  in  sub- 
stantial agreement  with  Kast's  figures.  Curiously  enough  the 
sample  of  nitroglycerine  from  supposedly  C.P.  glycerine  gave  the 
lowest  values,  pointing  to  some  impurity  in  the  glycerine  itself. 
In  consequence  another  specimen  of  refined  glycerine  was  taken 


44 


Original  Communications:  Eighth  International        [VOL. 


and  without  submitting  it  to  a  distillation  under  reduced  pressures 
as  in  the  previous  case,  it  was  nitrated  directly  at  a  temperature 
of  + 15°  C.  with  the  same  nitrating  acid  as  used  previously,  and  in 
this  way  after  carefully  washing,  drying  and  recrystallizing  twice 
by  a  process  of  partial  freezing  as  above,  was  obtained  as  a  per- 
fectly colorless  glistening  product.  It  was  then  dried  for  4  to  5 
days  in  a  vacuum  over  anhydrous  barium  oxide  and  phosphorus 
pentoxide.  This  specimen  (sample  No.  6)  gave  much  higher  values 
as  indicated  in  Table  II,  and  apparently  represented  a  much  purer 
specimen  than  sample  No.  4.  It  is  of  interest  as  pointing  to  the 
greater  purity  of  these  recrystallized  products,  that  the  time  taken 
to  obtain  the  maximum  reading  for  the  freezing-point  was  around 
18  to  20  minutes,  compared  with  9  to  12  minutes  in  the  earlier 
experiments,  showing  that  crystallization  took  place  more  slowly 
as  was  to  be  expected  with  a  purer  product. 

A  comparison  of  the  above  values  with  those  obtained  by  Nauck- 
hoff  and  Kast  is  given  below  in  Table  III. 


TABLE  III 


Description 

Labile 

Stable 

of  sample  of 

Appearance 

%  Nitro- 

Isomeride 

Isomeride 

ine  used 

F.  P. 

M.  P. 

F.  P. 

M  P 

°C. 

•C. 

°C. 

12.6 

Nauckhoff  (1905) 

C.P. 

Pale  Yellow 

18.48 

not  dete 

rmined 

12.3 

to 

12.4 

Kast  (1906) 

C.P. 

Almost  colorless 

18.50 

2.1 

2.8 

13.2 

13.5 

Nauckhoff  (1911) 

C.P. 

Almost  colorless 

not  dete 

rmined 

13.5 

13.5 

Hibbert  (1912) 

C.P. 

Colorless 

18.50 

1.8 

2.0 

12.9 

13.1 

No  appreciable  difference  was  found  in  the  individual  values 
for  the  freezing-  and  melting-point,  an  observation  not  altogether 
in  agreement  with  Kast's  figures  but  in  harmony  with  the  later 
work  of  Nauckhoff  (loc.  tit.). 

Solubility  of  the  Isomerides  in  Various  Solvents.  An  attempt 
was  made  to  ascertain  whether  some  difference  in  behavior  of 
the  two  isomerides  towards  various  solvents  could  not  be  detected 
and  for  this  purpose  solubility  experiments  were  carried  out  at 
— 10°  C.  At  this  temperature  both  dissolve  readily  in  acetone, 
ethyl  acetate,  ether,  methyl  and  ethyl  alcohol,  but  more  sparingly 


iv]  Congress  of  Applied  Chemistry  45 

in  butylene  nitrate.  They  are  insoluble  in  carbon  tetrachloride 
and  chloroform  at  the  same  temperature  of  — 10°  C. 

The  experiment  with  butylene  nitrate  was  carried  out  with  a 
view  to  making  molecular  weight  determinations  with  this  solvent, 
which  freezes  around  — 16°  C.,  and  our  experiments  served  to 
show  that  it  could  probably  be  made  to  serve  this  purpose. 

Sensitiveness  to  Shock  of  Liquid  Nitroglycerine  and  of  the  Two 
Solid  Isomerides.  Experiments  were  carried  out  by  allowing  a 
weight  of  two  pounds  to  drop  onto  the  substance  placed  in  the  cup 
of  a  steel  die  1  mm.  deep,  the  test  being  conducted  out  of  doors 
with  the  atmospheric  temperature  around  —1°  to  —  3°  C.  The 
liquid  product  was  supercooled  to  this  temperature  before  being 
used,  a  small  drop  being  placed  in  the  center  of  the  die,  while 
with  the  crystalline  isomerides  the  powdered  substance  was  placed 
on  the  bottom  of  the  die  in  a  thin  layer.  The  following  figures 
represent  the  maximum  height  at  which  no  explosion  occurred: 

Liquid  nitroglycerine  (substance  supercooled  to 

-2°  to  -3°  C.) 6  inches 

Stable  form,  M.P.  12.6°  C 10  to  12  inches 

Labile  form,  M.P.  1.0°  C 14  to  16  inches 

These  experiments  would  seem  to  establish  the  fact  that  the 
liquid  nitroglycerine  under  the  above  conditions  is  much  more 
sensitive  to  shock  than  either  of  the  two  solid  isomerides,  but  with 
regard  to  the  latter  a  point  which  should  be  mentioned  is  that  the 
stable  form  was  somewhat  more  finely  powdered  than  the  labile. 

Crystalline  Structure  of  the  Two  Isomerides.  Nauckhoff  in  his 
recent  paper  (loc.  cit.)  quotes  the  measurements  carried  out  for 
him  by  Flink  to  show  that  the  stable  form  of  nitroglycerine 
crystallizes  in  the  bipyramidal  class  of  the  rhombic  system,  and 
full  crystallographic  data  are  given  regarding  the  same.  A  crystal- 
lographic  investigation  conducted  by  us  with  the  kind  assistance 
of  Prof.  Amos  C.  Brown  of  the  University  of  Pennsylvania,  using 
the  polarizing  microscope,  convinced  us  of  the  accuracy  of  the 
above  classification,  and,  as  Nauckhoff  was  unable  to  obtain  the 
labile  isomeride,  we  have  also  undertaken  an  investigation  of  its 
crystalline  structure,  and  there  appears  to  be  little  doubt  (judging 


46  Original  Communications:  Eighth  International        [VOL. 

from  measurements  of  the  angle  of  extinction,  etc.,  made  by  means 
of  the  polarizing  microscope)  that  the  body  crystallizes  in  the 
triclinic  system.  We  were  fortunate  in  securing  excellent  photo- 
micrographs of  both  forms,  prints  of  which  are  shown  on  the  follow- 
ing pages.  In  this  connection  it  should  be  pointed  out  that  both 
for  crystallographic  and  microscopic  work  on  the  labile  isomeride 
it  is  strongly  advisable  to  use  nitroglycerine  which  has  been  re- 
cently made  and  not  previously  frozen,  since  the  product  thus 
obtained  apparently  does  not  change  into  the  stable  form  so  readily. 

Conditions  Influencing  the  Transformation  of  the  Labile  into  the 
Stable  Isomeride.  It  must  be  stated  at  once  that  while  in  every 
case  when  cooled  nitroglycerine  was  inoculated  with  either  form 
the  same  isomeride  crystallized  out,  yet  in  no  case  was  it  found 
possible  to  convert  the  higher  melting  isomeride  (stable  form)  di- 
rectly into  the  lower  melting  (labile  form)  without  proceeding 
through  the  liquid  phase.  On  the  other  hand  the  introduction  of  a 
trace  of  the  stable  isomeride  into  the  solid  or  partially  melted 
labile  form  caused  a  practically  instantaneous  and  complete 
transformation  of  the  labile  into  the  higher  melting  product, 
accompanied  by  a  considerable  rise  in  temperature  as  indicated 
in  the  following  experiments: 

A  quantity  of  10  grams  of  the  frozen  labile  form  was  cooled  to 
—  2°  to  —  4°  C.  and  then  the  product  inoculated  with  a  quantity 
of  the  stable  isomeride,  introduced  on  the  end  of  the  thermometer 
bulb.  The  mixture  was  stirred  vigorously  causing  the  labile  isom- 
eride to  change  over  almost  instantly  into  the  stable  modifica- 
tion, accompanied  by  a  rise  in  temperature  of  some  10°  C.,  such 
rise  taking  place  within  30  to  40  seconds.  When  a  similar  experi- 
ment was  tried  with  liquid  nitroglycerine,  supercooled  to  the  same 
temperature,  the  rise  in  temperature  on  inoculating  with  the  stable 
form  was  approximately  of  the  same  order  of  magnitude,  so  that 
apparently  the  heat  evolved  in  the  change  from  the  liquid  to  the 
labile  form  would  seem  to  be  much  less  pronounced  in  character, 
the  principal  "  energy-change  "  apparently  being  found  in  the 
conversion  of  the  lower  melting  solid  into  the  higher  melting  solid. 

At  temperatures  below  1°  C.  the  change  (lower-melting  isomeride 

»  higher-melting  isomeride)  is  apparently  an  irreversible  one. 

The  crystalline  labile  isomeride  may  be  kept  for  a  considerable 


rv]  Congress  of  Applied  Chemistry  47 

time  (one  to  two  weeks)  without  change  but  the  crystals  then 
slowly  lose  their  transparency,  becoming  opaque  and  the  body  is 
slowly  converted  into  the  higher  melting  derivative.  The  ease  of 
transformation  of  the  lower  melting  into  the  higher  melting  product 
apparently  depends  on  a  number  of  various  subtle  conditions. 
Thus,  for  example,  the  labile  form  prepared  from  nitroglycerine 
which  has  been  previously  frozen  as  the  stable  modification  would 
appear  to  be  more  easily  converted  into  the  stable  isomeride  than 
when  the  labile  product  is  obtained  from  recently  prepared  nitro- 
glycerine which  either  has  not  been  frozen  or  at  least  only  as  the 
labile  isomeride.  In  the  former  case  the  application  of  friction, 
such  as  rubbing  the  product,  prepared  either  at  —20°  C.,  —40°  or 

—  60°  C.  with  a  glass  rod  was  in  general  sufficient  to  bring  about 
the  transformation;  in  fact  it  took  place  at  times  so  readily  that 
it  was  very  difficult  to  know  just  exactly  to  what  the  sudden  change 
over  into  the  higher  melting  product  was  due.     These  conditions 
were  not  found  to  arise,  however,  when  the  labile  form  was  pre- 
pared from  a  sample  of  nitroglycerine  freshly  prepared  and  not 
previously  frozen. 

The  following  experiments  were  all  carried  out  with  a  sample  of 
the  labile  form  prepared  from  recently  made  and  not  previously 
frozen  nitroglycerine. 

(A)  Effect  of  Friction.    The  labile  isomeride  could  not  be  con- 
verted into  the  stable  form  either  at  -5°,  -20°,  -40°  or  -60°  C. 
by  rubbing  vigorously  with  a  glass  rod. 

(B)  Effect  of  "Seeding"  the  Labile  with  the  Stable  Isomeride. 
When  a  quantity  of  the  labile  derivative  was  powdered  out  of 
doors  in  a  cold  mortar,  the  temperature  being  between  0°  and 

—  2°  C.,  and  a  trace  of  the  stable  isomeride  incorporated,  then 
although  there  was  no  suspicion  of  melting  visible,  the  whole 
mass  went  over  rapidly  into  the  stable  form,  thus  proving  that  the 
presence  of  the  "  solid "  stable  derivative  was  sufficient  to  induce 
the  change  into  the  labile  product.     This  experiment  is  of  con- 
siderable importance  as  indicated  later  in  the  theoretical  discus- 
sion, in  enabling  us  to  reach  a  decision  as  to  whether  the  deriva- 
tives in  question  are  "purely  physical"  or  "chemical"  isomerides. 


48  Original  Communications:  Eighth  International        [VOL. 

(C)  Effect  of  Various  Metallic  Salts  in  Inducing  the  Change, 

Labile »  Stable.  In  attempting  to  find  an  explanation  of  the 

fact  that  while  with  wood-pulp  and  not  previously  frozen  nitro- 
glycerine at  —40°  C.  the  labile  form  separates  out,  while  on  the 
other  hand,  with  a  mixture  of  the  same  nitroglycerine,  wood-pulp 
and  sodium  nitrate,  we  get  the  stable  isomeride  under  these  con- 
ditions, several  interesting  facts  came  to  light,  without,  however, 
enabling  us  to  solve  this  peculiar  problem.  It  was  thought  at 
first  that  the  phenomenon  was  possibly  connected  in  some  way 
with  the  isomorphism  of  sodium  nitrate  with  the  stable  form  of 
nitroglycerine,  but  this  was  soon  shown  to  be  without  foundation. 
The  further  possibility  that  the  sodium  nitrate  might  form  some 
kind  of  double  compound  with  nitroglycerine  which  would  be 
isomorphous  with  the  stable  form  was  disproved  by  saturating 
nitroglycerine  with  sodium  nitrate  at  the  ordinary  temperature, 
cooling  this  solution  to  —  40°  C.  and  "seeding"  with  the  labile 
isomeride.  The  product  crystallized  out  completely  as  the  labile 
modification  and  this  independent  of  whether  the  nitroglycerine 
employed  had  been  previously  frozen  or  not.  A  saturated  solu- 
tion of  either  potassium  or  ammonium  nitrate  behaved  similarly. 

Further  experiments  by  taking  respective  samples  of  nitroglycer- 
ine which  had  and  had  not  been  previously  frozen,  either  perfectly 
dry  or  containing  a  little  moisture,  "seeding"  with  the  labile  form, 
melting  this  completely  by  keeping  at  25°  C.  for  one  or  two 
minutes,  and  then  adding  powdered  sodium,  potassium  or  ammo- 
nium nitrate,  and  cooling  to  —40°  C.,  gave  rise  to  no  separation 
of  crystals,  but  on  scratching  the  walls  of  the  test  tube  vigorously 
with  a  glass  rod  under  the  surface  of  the  liquid,  the  "labile" 
derivative  separated  out  in  every  case.  The  experiments  seem  to 
prove  that  the  presence  of  the  metallic  salts  alone  is  not  sufficient 
to  cause  the  change  from  labile  into  stable.  When,  however,  the 
liquid  product  obtained  by  melting  the  labile  isomeride  was  kept 
in  the  liquid  condition  for  a  longer  period,  e.g.,  about  one  hour  at 
20°  C.,  the  product  could  not  be  induced  to  crystallize  by  cooling 
to  —40°  C.,  even  in  the  presence  of  the  above  salts.  Various 
other  experiments  were  tried,  e.g.,  by  inoculating  the  solid  labile 
form  obtained  from  not  previously  frozen  nitroglycerine  with  pow- 
dered sodium,  potassium  and  ammonium  nitrates,  and  rubbing 


* 


PHOTOMICROGRAPHS  OF  THE  STABLE  ISOMERIDE  OF  NITROGLYCERINE. 


iv]  Congress  of  Applied  Chemistry  49 

the  product  vigorously  with  a  glass  rod.  The  presence  of  sodium 
and  ammonium  nitrate  was  effective  in  bringing  about  the  con- 
version of  the  labile  into  the  stable  form  in  a  number  of  experi- 
ments tried,  but  under  the  same  conditions  no  such  conversion 
could  be  induced  when  potassium  nitrate  was  used.  This  marked 
difference  in  the  behavior  of  potassium  as  contrasted  with  that  of 
sodium  and  ammonium  nitrate  proved  to  be  an  outstanding 
feature  throughout  this  work,  since  neither  when  used  with  nitro- 
glycerine alone  nor  in  conjunction  with  wood-pulp,  glass-wool, 
etc.,  was  it  capable  of  inducing  the  conversion  of  the  labile  into 
the  stable  modification.  The  assumption  that  this  difference  in 
behavior  may  be  occasioned  by  some  impurities  in  the  sample  of 
sodium  nitrate  employed  would  seem  to  be  unwarranted,  since 
the  liquid  nitroglycerine  could  be  supercooled  in  the  presence  of 
the  same  sample  of  powdered  nitrate  and  no  crystallization  ensued. 
Also  as  stated  above  even  when  the  solid  labile  form  was  incor- 
porated with  the  powdered  sodium  nitrate  this  treatment  was  not 
always  successful  in  causing  the  conversion  of  the  labile  into  the 
stable  modification.  A  further  peculiarity  is  the  fact  that  when 
the  wood-pulp-sodium-nitrate  mixture  is  replaced  by  a  mixture 
of  ground  glass-wool  with  sodium  nitrate  the  behavior  of  these 
two  mixtures  with  not  previously  frozen  nitroglycerine  is  quite 
different,  since  in  the  latter  case  the  sodium  nitrate  apparently 
exerts  no  effect  on  the  labile  form,  this  latter  invariably  crystalliz- 
ing out  in  the  limited  number  of  experiments  carried  out  by  us. 
It  was  noticeable,  however,  that  when  the  sample  of  nitroglycerine 
employed  contained  moisture  the  labile  form  separating  out  showed 
a  much  more  marked  tendency  to  go  over  into  the  stable  isomeride, 
especially  on  rubbing  with  a  glass  rod.  Previous  experiments 
would  seem  to  indicate  that  the  change  of  the  labile  into  the  stable 
isomeride  is  not  generally  induced  by  friction  or  by  the  presence 
of  sodium  nitrate  or  wood-pulp  acting  alone,  but  arises  rather 
from  the  joint  action  of  all  three  factors.  In  view  of  the  fact  just 
mentioned  that  the  presence  of  moisture  seems  to  facilitate  the 
conversion  of  the  labile  form  when  a  metallic  salt  is  present,  the 
action  of  wood-pulp  may  possibly  be  connected  in  some  way  with 
its  moisture  content.  It  would  seem  next  to  impossible  to  give 
a  satisfactory  explanation  of  such  abnormal  behavior,  but  for  the 


50 


Original  Communications:  Eighth  International        [VOL. 


purpose  of  obtaining  a  general  oversight,  the  results  obtained  have 
been  tabulated  below.  The  procedure  in  each  case  was  to  cool 
the  product  first  to  —40°  C.  and  then  stir  it  vigorously  with  a  glass 
rod,  afterwards  to  transfer  a  trace  of  this  frozen  product  to  another 
sample  of  the  same  nitroglycerine  cooled  to  the  same  temperature, 
and  then  rub  the  inner  surface  of  the  test  tube  below  the  liquid 
vigorously  with  a  glass  rod  for  some  seconds. 

TABLE  IV 


No. 
of 
Exp. 

Description  of  sample 
of  nitroglycerine  used 

Mixture  incorpor- 
ated with  the 
nitroglycerine 

Temperature 
to  which  prod- 
uct was  cooled 

Nature  of 
product  separating 
out 

1 

2 
3 

4 
5 

The  nitroglycerine  was  em- 
ployed both  as  the  pre- 
viously and  not  previous- 
ly frozen  product,  also  an- 
hydrous and  containing  a 
little  moisture. 

Same 

Sodium  nitrate 
and  wood-pulp 

Potassium  nitrate 
and    wood-pulp 
or  glass-wool 

Ammonium        ni- 
trate and  wood- 
pulp    or    glass- 
wool 

Sodium  nitrate 
and  glass-wool 

Same 

—  40°  C. 

—  40°  C. 
—  40°  C 

—  40°  C. 
—  40°  C. 

Stable  isomeride  almost  in- 
variably, though  labile 
form     appeared     tran- 
siently in  many  cases. 

Labile  isomeride   invari- 
ably obtained. 

Labile     isomeride     sepa- 
rated out  almost  invari- 
ably. 

The  labile  isomeride  sepa- 
rated  but   presence   of 
moisture  seemed  to  give 
a   product   more   easily 
converted       into       the 
stable  form. 

Sometimes  the  labile  and 
sometimes    the     stable 
isomeride. 

Same      

Nitroglycerine      not     pre- 
viously frozen. 

Nitroglycerine     previously 
frozen. 

As  far  as  our  experiments  go  there  appears  to  be  no  doubt  but 
that  previously  frozen  nitroglycerine  freezes  much  more  readily 
than  not  previously  frozen,  and  this  is  especially  true  with  recently 
frozen  samples.  When  nitroglycerine  is  frozen  as  the  labile  form, 
then  melted  and  kept  in  the  liquid  state  for  not  more  than  about 
one  minute,  the  labile  isomeride  was  found  to  separate  out  again 
on  cooling  to  —40°  C.,  while  when  frozen  as  the  stable  derivative, 
then  melted  and  again  cooled,  the  stable  modification  crystallizes 
out  when  "seeding"  is  not  resorted  to.  If  nitroglycerine  is  first 
frozen  as  the  labile  isomeride,  then  melted  completely,  this 
" seeded"  with  the  stable  form,  the  stable  isomeride  so  obtained, 
melted  for  two  or  three  minutes,  cooled  and  then  " seeded"  with 


iv]  Congress  of  Applied  Chemistry  51 

the  labile  form,  the  labile  isomeride  thus  obtained  melted  for 
about  one  minute,  and  then  cooled  without  further  inoculation, 
we  get  the  labile  modification  crystallizing  out,  which,  however, 
under  these  conditions  changes  over  almost  immediately  into  the 
stable  isomeride  on  rubbing  with  a  glass  rod.  It  is  an  interesting 
fact  that  the  labile  isomeride  can  be  melted,  the  liquid  product 
heated  to  a  temperature  of  20°  to  30°  C.,  i.e.,  some  8°  to  18°  C. 
above  the  melting  point  of  the  stable  form,  maintained  there  for 
one  minute,  and  then  on  cooling  to  —40°  C.  and  scratching  the 
inner  surface  of  the  tube  can  be  caused  to  separate  again  as  the 
labile  modification.  The  above  change  occurs  when  the  labile 
form  is  kept  only  for  a  short  period  as  indicated  at  a  temperature 
of  20°  to  30°  C.  With  a  longer  period  than  this  it  was  not  found 
possible  to  induce  spontaneous  crystallization  of  either  form, 
though  as  far  as  could  be  judged  no  trace  of  solid  was  left  in  the 
first  experiment,  this  being  shown  by  the  fact  that  cooling  alone 
to  —40°  C.  produced  no  crystallization,  this  being  only  induced 
by  scratching  with  a  glass  rod.  These  experiments  would  seem 
to  indicate  that  the  two  isomerides  may  exist  in  the  liquid  state, 
but  if  we  conclude,  as  is  assumed  later,  that  we  are  dealing  only 
with  ''physical"  isomerides,  then  the  work  of  Schaum  (Ann.  300, 
209  [1898])  and  others  does  not  bear  out  such  a  contention. 

We  were  not  successful  in  effecting  the  crystallization  of  nitro- 
glycerine at  a  temperature  of  —17°  to  —20°  C.  (even  on  standing 
for  24  hours)  with  recently  made  and  not  previously  frozen  samples, 
even  when  vigorous  scratching  of  the  walls  of  the  test  tube  by  a 
glass  rod  was  resorted  to.  Furthermore,  at  this  temperature  the 
addition  of  wood-pulp  alone  or  wood-pulp  with  sodium,  potassium 
or  ammonium  nitrate  used  individually  or  collectively  was  in- 
effective in  bringing  about  the  crystallization  of  the  nitroglycerine 
at  this  temperature,  while  with  a  previously  and  especially  a  re- 
cently frozen  product  the  freezing  could  be  induced  without  very 
much  difficulty  without  any  addition  or  inoculation. 

THEORETICAL  DISCUSSION 

It  is  necessary  at  the  outset  to  consider  whether  in  the  case  of 
the  two  isomeric  forms  of  nitroglycerine  described  above  we  are 
dealing  with  "purely  physical"  as  distinct  from  " chemical" 


52  Original  Communications:  Eighth  International        [VOL. 

isomerides.  In  the  first  place  it  cannot  be  stated  with  certainty 
that  we  are  not  simply  dealing  with  two  polymers,  and  this  ques- 
tion cannot  be  decided  until  molecular  weight  determinations  of 
the  two  forms  have  been  made,  for  which  purpose  butylene  glycol 
dinitrate,  which  freezes  around  — 16°  C.,  would  probably  serve 
as  a  good  solvent.  There  is  also  the  point  that  " structural" 
isomerism  is  possible  as  indicated  by  the  two  formulae  ("  A"  and 
"B")  shown  below: 

0 

.0  CH2-0-N/ 


'% 


CH2-0-N^_  /  \ 

CH— 0— N 

CH2-0-N£  I         °\  /° 

V)  (W-O-N 


\ 


"A"  "B" 


However,  a  review  of  the  experimental  evidence  obtained,  and 
especially  in  view  of  the  extraordinary  far-reaching  analogy  be- 
tween these  derivatives  and  the  two  isomeric  forms  of  benzophe- 
none  convinces  us  that  we  are  dealing  here  with  a  case  of  "  physical" 
rather  than  with  one  of  "chemical"  isomerism.  In  a  very  inter- 
teresting  paper  on  isomerism  published  some  years  ago  by  Schaum 
(Ann.  1898,  800,  p.  209),  the  question  of  physical  and  chemical 
isomerism  is  discussed  very  thoroughly  from  a  physico-chemical 
standpoint,  with  especial  reference  to  the  case  of  the  two  isomeric 
forms  of  benzophenone.  According  to  this  author  the  criterion 
between  chemical  and  physical  isomerism  is  to  be  found  in  the  fact 
that  with  purely  physical  isomerides,  inoculation  of  the  solid 
labile  with  the  solid  stable  form  brings  about  the  complete  con- 
version of  the  former  in  the  absence  of  any  solvent.  If  it  is  not 
possible  to  convert  the  solid  labile  form  into  the  solid  stable  iso- 
meride  directly,  i.e.,  by  simple  inoculation,  but  only  by  passing 
through  the  liquid  phase  or  by  the  use  of  a  solvent,  then  we  are 


iv]  Congress  of  Applied  Chemistry  53 

dealing,  according  to  Schaum,  with  " chemical"  isomerides. 
From  his  own  experimental  work  and  that  of  others,  this  author 
arrives  at  the  conclusion  that  physical  isomerism  does  not  exist 
in  the  liquid  but  only  in  the  soild  state;  in  other  words,  the  liquids 
obtained  by  melting  both  forms  are  identical  in  character.  Viewed 
from  this  standpoint,  the  two  isomeric  forms  of  benzophenone  are 
physical,  not  chemical  isomerides.  Since  the  solid  labile  form  of 
nitroglycerine  when  incorporated  with  the  stable  form  goes  over 
practically  instantaneously  into  the  higher  melting  isomeride 
(page  17)  no  solvent  being  present,  it  would  seem  that  we  are  also 
dealing  here  with  physical  rather  than  chemical  isomerides.  In 
order  the  better  to  grasp  the  analogy  between  the  isomeric  forms 
of  nitroglycerine  and  those  of  benzophenone,  the  properties  of 
the  latter  are  quoted  below  in  brief  form. 

The  stable  form  of  benzophenone  melts  afc  48°  to  49°  C.  and  the 
second  isomeride  (labile  form)  at  26°  to  27°  C.  This  latter  deriva- 
tive was  discovered  by  Zincke  in  1871  (Ann.  159,  p.  377)  who 
prepared  it  by  the  distillation  of  benzophenone  obtained  as  an 
oxidation  product  from  diphenylmethane.  He  showed  that  its 
behavior  with  solvents  was  different  from  that  of  the  stable  form, 
e.g.,  it  could  not  be  recrystallized  from  alcohol,  etc.,  and  apparently 
crystallizes  in  the  monoclinic  system,  the  stable  on  the  other  hand 
belonging  to  the  rhombic  class.  The  transparent  crystals  of  the 
labile  isomeride  after  standing  for  several  weeks  become  opaque, 
changing  over  slowly  into  the  stable  modification.  When  a  quan- 
tity of  the  labile  isomeride  was  inoculated  with  a  trace  of  the 
stable  form  there  was  an  instantaneous  conversion  into  the  higher 
melting  derivative  accompanied  by  evolution  of  considerable  heat. 
If  a  sample  of  supercooled  liquid  benzophenone  is  inoculated 
simultaneously  at  different  points  with  a  trace  of  both  isomerides, 
both  forms  develop,  though  the  stable  form  separates  out  much 
more  rapidly  and  in  a  short  time  the  whole  product  is  converted 
into  the  stable  modification.  It  was  not  found  possible  to  re- 
convert the  solid  stable  isomeride  directly  into  the  solid  labile 
form. 

Later  work  by  K.  Auwers  and  V.  Meyer,  Ber.  1889,  22,  550, 
developed  the  following  facts:  The  most  reliable  method  for 
obtaining  the  labile  form  consists  in  preparing  freshly  distilled 


54 


Original  Communications:  Eighth  International        [VOL. 


benzophenone  and  cooling  this  to  0°  C.  The  liquid  distillate  may 
be  kept  at  room  temperature  for  days  without  solidifying  but  on 
cooling  to  0°  C.  it  crystallizes  out  more  or  less  slowly  as  the  lower 
melting  labile  form.  It  can  then  be  melted,  solidified,  and  re- 
melted  repeatedly  without  change,  but  if  the  solid  product  is 
rubbed  with  a  glass  rod  or  pestle,  or  if  a  trace  of  the  solid  stable 
form  is  introduced,  we  have  an  immediate  conversion  of  the  labile 
into  the  stable  isomeride  accompanied  by  a  considerable  rise  in  tem- 
perature. 

In  the  article  referred  to  above,  Schaum  shows  that  it  is  not 
necessary  to  heat  benzophenone  to  the  boiling  point  in  order  to 
obtain  the  labile  modification,  that  although  this  is  a  reliable 
method,  yet  it  is  possible  by  heating  the  stable  form  to  only  a  few 


iv]  Congress  of  Applied  Chemistry  55 

degrees  above  its  melting  point  and  then  cooling,  to  occasionally 
obtain  the  labile  modification.     He  points  out  further  that 

"Wenn  wir  beispielweise  fluessiges  Benzophenon  unterkuehlen 
so  kommen  wir  in  das  metastabile  Gebiet.  Beim  Ueberschreiten 
der  Metastabilitaetsgrenzen  bei  fallender  Temperatur  gelangt 
dann  der  Koerper  in  ein  labiles  Gebiet  in  welchem  er  sich  auch 
bei  Keimfreiheit  in  eine  stabilere  Form  unwandeln  muss,"  and 
in  fact  was  able  to  show  that  with  the  product  in  the  metastable 
condition  indicated  in  the  quotation  above,  the  vibration  or  shock 
caused  by  scratching  the  sealed  glass  tube  containing  the  benzo- 
phenone  with  a  file,  provided  a  sufficient  disturbance  to  cause  the 
change  over  into  the  stable  modification.  However,  to  properly 
characterize  the  "metastable  condition"  he  considers  it  necessary 
to  add  (p.  217):  "Ausser  der  Anwesenheit  der  stabilen  Phase 
auch  noch  allerhand  aeussere  Einwirkungen  die  Umwandlung 
hervorzubringen  im  Stande  sind,"  a  statement  which  we  can 
heartily  support  in  view  of  the  anomalous  results  met  with  by  us 
in  the  examination  of  the  nitroglycerine  isomerides. 

A  careful  review  of  the  experimental  work  performed  on  the 
isomeric  forms  of  nitroglycerine  shows  that  the  above  properties 
of  benzophenone  are  almost  identical  in  every  respect  with  those 
of  the  nitroglycerine  isomerides.  Thus,  for  example,  the  labile 
form  of  nitroglycerine  can  only  be  obtained  with  certainty  by  one 
method,  viz.,  the  use  of  a  freshly  prepared,  not  previously  frozen 
product.  Further,  it  is  converted  into  the  stable  form  instantly 
by  direct  inoculation  and  slowly  on  standing  at  ordinary  tempera- 
ture. The  stable  cannot  be  reconverted  directly  into  the  labile 
form,  and  when  used  to  inoculate  supercooled  liquid  nitroglycerine 
simultaneously  with  the  labile  form  it  crystallizes  out  more  rapidly 
than  the  latter,  finally  causing  the  solidification  to  take  place 
entirely  as  the  stable  derivative.  On  rubbing  with  a  glass  rod,  the 
labile  form  was  in  a  number  of  cases  (dependent  on  the  mode  of 
preparation)  transformed  into  the  stable  isomeride,  and  in  harmony 
with  the  behavior  of  the  labile  form  of  benzophenone  the  labile 
isomeride  of  nitroglycerine  could  be  melted  and  solidified  re- 
peatedly without  change.  It  is  also  a  curious  fact  that  both  the 
stable  form  of  nitroglycerine  and  that  of  benzophenone  crystallize 
in  the  rhombic  system,  the  labile  form  of  nitroglycerine  crystalliz- 


56  Original  Communications:  Eighth  International        [VOL. 

ing  in  the  triclinic  and  possibly  also  that  of  benzophenone,  since 
Zincke  (loc.  tit.)  gives  the  monoclinic  system  for  this  body  but 
admits  the  uncertainty  of  his  identification.  Finally,  as  indicated 
on  page  17,  there  is  considerable  heat  evolved  in  the  change  from 
the  labile  into  the  stable  isomeride.  It  would  be  difficult  to  im- 
agine a  closer  analogy  than  between  the  isomeric  forms  of  these 
two  substances.  The  assumption  would  appear  to  be  justified 
that  we  are  also  dealing  in  the  case  of  nitroglycerine  with  a  case  of 
"physical"  and  not  "chemical"  isomerism,  i.e.,  that  the  two 
derivatives  differ  only  in  the  "energy-value"  represented  by  their 
different  crystalline  structures. 

Sensitiveness  of  Frozen  Dynamite  to  Shock.  The  view  previously 
held  by  many  technical  chemists  that  frozen  dynamite  is  more 
sensitive  to  shock  than  the  liquid  product  is  gradually  being 
abandoned,  and  as  indicated  in  our  own  experiments  on  the  "  drop 
test "  is  incorrect.  It  must,  however,  be  pointed  out  that  such 
remarks  refer  to  the  products  themselves  and  not  to  the  conditions 
arising  during  the  change  of  physical  state  when  the  liquid  passes 
over  into  either  of  the  two  solid  forms.  It  has  been  shown  that 
the  labile  isomeride  may  be  induced  to  go  over,  under  certain 
conditions,  practically  spontaneously  into  the  stable  modification, 
considerable  heat  being  evolved  in  the  process.  It  is  difficult  to 
imagine  that  the  heat  thus  evolved  could  provide  a  sufficient 
"  energy-stimulus  "  to  induce  a  premature  explosion;  rather  are 
the  conditions  for  such  to  be  sought  for,  in  all  probability  in  the 
peculiar  synchronistic  state  possessed  by  the  nitroglycerine  mole- 
cule in  the  actual  change  of  the  liquid  into  the  solid  state  or  espe- 
cially during  that  of  the  lower  into  the  higher  melting  isomeride, 
the  latter  being  possibly  analogous  to  the  change  of  state  of  the 
yellow  modification  of  mercuric  iodide  into  the  red  variety  brought 
about  by  rubbing  with  a  metallic  substance. 

CONCLUSIONS 

1.  It  has  been  shown  that  solid  nitroglycerine  exists  in  two 
forms,  a  labile  and  a  stable  isomeride  possessing  the  following 
freezing-  and  melting-points: 

Labile  Form  Stable  Form 

F.P.  1.9°  C.  F.P.  13.0°  C. 

M.P.  2.0°  C.  M.P.  13.2°  C. 


rv]  Congress  of  Applied  Chemistry  57 

which  values  are  in  substantial  agreement  with  those  obtained  by 
Kast  and  Nauckhoff. 

2.  Methods  for  the  preparation  of  both  isomeric  forms  have  been 
developed  and  their  various  physical  properties,  solubility  in  sol- 
vents, sensitiveness  to  shock,  crystallographic  structure,  the  con- 
ditions under  which  one  is  converted  into  the  other,  and  the 
influence  of  metallic  salts  in  effecting  such  conversion  have  been 
investigated.     Photomicrographs  of  both  isomerides  have  also 
been  prepared. 

3.  The  substitution  of  potassium  for  sodium  nitrate  in  the 
"  dope  "  employed  in  making  dynamite  would  presumably  give  a 
product  freezing  at  a  lower  temperature,  since  with  the  former  salt 
there  is  no  tendency  towards  the  formation  of  the  higher-melting 
stable  isomeride,  although  we  are  not  aware  of  any  observations 
indicating  that  dynamite  made  with  commercial  saltpetre  is  more 
difficult  to  freeze  than  that  made  with  sodium  nitrate. 

4.  The  extraordinarily  far-reaching  analogy  between  the  iso- 
meric forms  of  nitroglycerine  and  benzophenone  has  been  com- 
mented upon  and  the  evidence  pointed  out  in  favor  of  regarding 
the  isomerism  as  "  physical"  rather  than  "  chemical." 

The  author  wishes  to  express  his  thanks  to  the  Director  of  the 
Experimen  tall  Station  and  the  officials  of  the  duPont  Powder 
Company  for  their  kind  permission  to  publish  the  preceding 
investigation. 


BOILING  POINTS  OF  SOLUTIONS  OF  NITROGLYCERIN 

BY  A.  L.  HYDE 
Bureau  of  Mines,  Pittsburgh,  Pa. 

The  following  work  is  the  result  of  an  attempt  to  obtain  a  method 
for  determin'ng  approximately  the  mean  molecular  weight  of 
mixtures  of  nitroglycerin  with  allied  bodies.  The  determination 
of  rise  in  boiling  point  seemed  to  be  the  most  promising  method 
since  most  of  the  solvents  for  nitroglycerin  freeze  at  so  low  a 
temperature  as  to  make  the  freezing-point  method  not  feasible. 
From  the  nature  of  the  case  no  very  exact  determinations  could 
be  expected  from  the  boiling-point  method,  but  it  was  thought 
that  by  using  fairly  concentrated  solutions  so  that  the  rise  in 
boiling  point  would  be  considerable,  information  of  some  value 
might  be  obtained.  Accordingly  all  the  solutions  used  were  of 
considerable  concentration. 

The  apparatus  used  was  a  slight  modification  of  the  ordinary 
molecular-weight  apparatus  of  Beckmann.  Since  it  was  important 
that  the  concentration  of  the  solutions  should  change  as  little 
as  possible  during  the  observation,  it  was  necessary  to  condense 
the  vaporized  solvent  as  near  to  the  boiling  solution  as  possible. 
This  was  done  by  means  of  a  coil  of  copper  tubing  wound  around 
the  outside  of  the  tube  containing  the  solution.  This  coil  was 
just  above  the  surface  of.  the  solution  and  cold  water  was  kept 
circulating  through  it.  In  this  way  only  a  small  fraction  of  the 
solvent  was  at  any  time  away  from  the  main  body  of  the  solution. 
Heating  of  the  solution  was  accomplished  by  means  of  a  coil  of 
fine  platinum  wire  sealed  into  the  bottom  of  the  tube  and  heated 
by  an  electric  current.  In  this  way  the  heating  was  done  within 
the  body  of  the  solution  instead  of  from  the  outside  and  over- 
heating was  avoided.  The  thermometer  used  was  an  ordinary 
Beckmann  reading  to  hundredths  of  a  degree. 

The  procedure  was  as  follows :  A  suitable  quantity  of  the  pure 
solvent  was  poured  into  the  tube  and  the  thermometer  inserted. 
The  solvent  was  then  boiled  and  when  equilibrium  was  established 
the  boiling  point  was  noted.  The  tube  was  then  emptied  and 

59 


60  Original  Communications:  Eighth  International        [VOL. 

dried.  A  quantity  of  nitroglycerin  was  then  placed  in  a  small 
tared  beaker  and  accurately  weighed.  A  suitable  quantity  of 
solvent  was  poured  upon  the  nitroglycerin,  the  beaker  rotated 
until  a  homogeneous  solution  was  obtained  and  the  total  solution 
weighed.  This  solution  was  quickly  transferred  to  the  apparatus 
and  its  boiling  point  determined  under  the  same  conditions  as 
that  of  the  pure  solvent.  The  difference  in  the  boiling  points 
after  proper  correction  represents  the  influence  of  the  quantity 
of  nitroglycerin  present.  After  several  determinations  the  boiling 
point  of  the  pure  solvent  was  again  determined  to  find  if  there 
had  been  any  change  due  to  variation  in  atmospheric  pressure. 
In  case  of  change,  usually  only  a  few  hundredths  of  a  degree,  it 
was  assumed  that  the  rate  of  change  had  been  constant  and  cal- 
culations made  accordingly. 

Assuming  that  the  law  for  dilute  solutions  holds  also  in  the  case 
of  concentrated  solutions,  the  molecular  weight  of  nitroglycerin 

should  be  given  by  the  formula,  m=— ,  where  g  is  grams  of  nitro- 

a 

glycerin  per  100  grams  of  solvent  a  is  the  rise  in  boiling  point, 
and  r  is  the  boiling  point  constant  of  the  solvent  used.  As  a 
matter  of  fact,  it  will  be  shown  that  this  law  does  not  hold  true 
in  most  concentrated  solutions  of  nitroglycerin.  Only  one  of 
the  solvents  tried  shows  even  approximate  conformity  to  this 
law.  The  solvents  tried  were  ether,  acetone,  methyl  alcohol, 
chloroform,  and  ethyl  acetate.  The  results  with  each  of  these 
are  given  below. 

Ether.  Several  precautions  are  necessary  when  using  ether  as 
a  solvent.  In  the  first  place,  the  low  boiling  point  of  ether  makes 
its  solutions  more  subject  to  changes  in  concentration  than  is 
the  case  when  higher  boiling  solvents  are  used.  Hence  the  weighing 
should  be  made  in  a  stoppered  weighing  bottle  and  both  weighing 
and  transfer  to  the  boiling-point  apparatus  should  be  as  rapid  as 
possible.  The  low  boiling  point  also  makes  necessary  a  consider- 
able condensing  surface  hi  the  apparatus  to  prevent  escape  of 
part  of  the  solvent.  Again,  the  electric  current  used  for  heating 
must  be  carefully  regulated,  since  excessive  heating  of  the  platinum 
wire  in  contact  with  ether  causes  formation  of  formaldehyde. 


iv]  Congress  of  Applied  Chemistry  61 

This  of  course  changes  the  boiling  point.  Below  are  results  ob- 
tained with  ether  as  solvent.  In  this  table,  (g)  represents  grams 
of  nitoglycerin  in  100  grams  of  solvent,  (a)  represents  rise  in 
boiling  point  in  degrees  Centigrade,  and  (m)  is  the  apparent  mole- 

or  j1 

cular  weight  of  nitroglycerin  calculated  by  the  formula,  m  =  — . 

a 

The  value  of  (r)  used  is  21.1,  which  is  the  value  for  ether  given  in 
the  Chemiker  Kalender,  1910. 

gam 
10.81  .86  264 

17.70  1.35  277 

34.51  2.29  318 

72.63  3.79  404 

Since  the  theoretical  molecular  weight  of  nitroglycerin  is  227, 
these  results  seem  to  indicate  that  in  concentrated  ether  solutions 
of  nitroglycerin  there  is  association  of  the  molecules  of  nitrogly- 
cerin and  that  this  association  increases  with  increase  of  concen- 
tration. 

Acetone.  Only  two  determinations  were  made  with  acetone 
as  a  solvent.  These  results  are  as  follows,  the  value  of  (r)  used 
in  calculating  (m  being  16.7). 

gam 
21.00  1.68  209 

48.19  4.26  189 

These  results  as  far  as  they  indicate  anything  indicate  a  dissocia- 
tion of  the  nitroglycerin  molecule  instead  of  an  association  as 
was  the  case  when  ether  was  used  as  solvent. 

Methyl  alcohol.  The  boiling-point  constant  (r)  for  methyl 
alcohol  is  low — 8.8.  This  makes  necessary  the  use  of  very  concen- 
trated solutions  of  nitroglycerin  if  the  rise  in  boiling  point  is  to 
be  considerable.  Accordingly  the  solutions  with  methyl  alcohol 
as  solvent  were  considerably  more  concentrated  than  the  ether 


62 

Original  Communications:  Eighth  International        [VOL. 

solutions  already  mentioned, 
as  follows: 

g 
17.54 
39.03 
75.10 
111.38 

The  results  with  this  solvent  were 

a                     m 
.55                 281 
1.21                 284 
2.01                 328 
2.56                 383 

Like  the  results  with  ether,  these  results  seem  to  indicate  an 
association  of  the  nitroglycerin  molecules.  Also  the  association 
increases  with  increase  of  concentration,  though  the  degree  of 
association  is  not  as  great  as  with  ether  solutions. 

Chloroform.  The  boiling-point  constant  for  chloroform  as  a 
solvent  is  36.6.  Hence  the  solutions  used  were  not  as  concentrated 
as  the  methyl  alcohol  solutions.  Below  are  results  with  this 
solvent. 

gam 
14.69  1.66  324 

29.26  2.69  398 

57.67  3.97  532 

74.93  4.59  598 

An  inspection  of  these  results  shows  a  very  great  degree  of  associa- 
tion of  the  nitroglycerin  molecules.  The  highest  concentration 
tried  shows  an  apparent  molecular  weight  of  considerably  more 
than  twice  the  theoretical.  Even  the  lowest  concentration  used 
gives  a  molecular  weight  far  above  theoretical.  Here  again  as 
was  the  case  with  ether  and  methyl  alcohol,  increased  association 
is  shown  with  increased  concentration. 

Ethyl  acetate.  Results  using  ethyl  acetate  as  solvent  are  given 
below.  The  value  of  (r)  used  for  calculating  (m)  is  26.1. 

gam 
10.60  1.18  234 

22.30  2.47  235 

29.00  3.65  235 

34.66  3.95  229 

35.15  3.97  231 


rv]  Congress  of  Applied  Chemistry  63 

Of  the  solvents  used,  this  is  the  only  one  whose  rise  in  boiling  point 
is  approximately  proportional  to  the  concentration  even  at  the 
rather  high  concentrations  used.  The  uncertainty  of  the  deter- 
mination of  the  value  (a)  with  the  apparatus  used  is  probably 
several  hundredths  of  a  degree  so  that  the  calculated  value  of 
(m)  when  using  this  solvent  at  least  approximates  the  theoretical 
value. 

Inspection  of  the  results  obtained  with  these  five  common  sol- 
vents for  nitroglycerin  shows  that  of  the  five,  ethyl  acetate  alone 
gives  results  nearly  independent  of  concentration.  Hence  if  it 
is  desired  to  obtain  approximately  the  mean  molecular  weight  of 
a  mixture  containing  nitroglycerin,  this  is  the  only  one  of  the 
solvents  tried  which  is  available.  Ethyl  acetate  is  a  good  solvent 
for  most  of  the  substance's  which  are  likely  to  occur  in  the  ether 
extract  of  explosives.  It  is  therefore  well  suited  for  the  purpose 
in  view. 

An  example  of  the  use  of  the  method  as  a  check  upon  other 
determinations  may  be  given.  The  ether  extract  from  a  certain 
explosive  is  supposed  to  consist  of  a  mixture  of  nitroglycerin  and 
tetranitrodiglycerin.  Since  the  molecular  weight  of  the  latter  is 
346,  a  mixture  of  the  two  should  show  a  mean  molecular  weight 
considerably  higher  than  pure  nitroglycerin.  Two  determinations 
were  made  upon  this  mixture  with  following  results : 

gam 
30.50  3.06  260 

35.10  3.50  262 

This  molecular  weight  corresponds  to  a  percentage  of  about  29 
per  cent  of  tetranitrodiglycerin  in  the  mixture. 

A  nitrogen  determination  of  the  mixture  in  the  nitrometer  gave 
a  nitrogen  content  of  17.74  per  cent.  Since  tetranitrodiglycerin 
contains  16.19  per  cent  nitrogen  and  nitroglycerin  contains  18.5 
per  cent  nitrogen,  the  nitrogen  content  found  corresponds  to 
about  33  per  cent  of  tetranitrodiglycerin  in  the  mixture.  Con- 
sidering the  fact  that  a  variation  of  only  .10  per  cent  in  the  nitro- 
gen content  found  will  make  a  difference  of  over  4  per  cent  in 
the  apparent  amount  of  tetranitrodiglycerin  present,  the  results 
obtained  by  the  two  methods  agree  fairly  well. 


64  Original  Communications:  Eighth  International        [VOL. 

These  facts  lead  to  the  conclusion  that  a  fairly  satisfactory 
determination  of  mean  molecular  weight  of  nitroglycerin  mixtures 
may  be  made  by  noting  rise  in  boiling  point  of  ethyl  acetate  solu- 
tions of  these  mixtures. 

A  few  observations  upon  the  above  results,  though  not  bearing 
upon  the  problem  in  hand,  may  be  given  for  what  they  are  worth. 
In  the  results  with  the  solvents  ether,  methyl  alcohol,  and  chloro- 
form, though  the  rise  in  boiling  point  does  not  follow  the  law  for 
dilute  solutions,  yet  there  is  a  certain  regularity.  Consider  first 
the  results  with  chloroform.  If  the  values  of  (g)  and  (a)  be  plotted 
on  the  x  and  y  axes  respectively  of  a  system  of  co-ordinates,  the 
points  obtained  lie  along  an  apparently  regular  curve.  If  the 
rise  in  boiling  point  (a)  were  directly  proportioned  to  the  con- 
centration (g)  as  in  dilute  solutions,  this  curve  would  of  course  be 
a  straight  line.  But  the  values  actually  found  give  a  curve  which 
bends  towards  the  x  axis  as  concentration  increases.  Though 
this  curve  appears  to  be  a  regular  one,  attempts  to  find  a  simple 
algebraic  expression  for  it  were  unsuccessful.  If,  however,  the 
concentration  (g),  instead  of  representing  grams  of  nitroglycerin 
per  100  grams  of  chloroform,  be  expressed  in  grams  of  nitrogly- 
cerin per  100  grams  of  total  solution,  the  curve  obtained  seems  to 
follow  a  simple  law. 

If  the  values  of  (g)  be  recalculated  thus  and  these  values  be 
called  (h),  will  then  be  the  percentage  concentration  of  the  solu- 
tions. The  values  of  (h)  corresponding  to  the  values  of  (a)  with 
chloroform  as  solvent  are  as  follows: 

a  =  1.66  h  =  12.8 

a  =  2.69  h  =  22.7 

a  =  3.97  h  =  36.6 

a  =  4.59  h  =  42.3 

Now,  if  the  variations  from  the  law  of  dilute  solutions  are  really 
due  to  association  of  the  molecules,  it  seems  reasonable  to  suppose 
that  this  association  should  be  a  function  of  the  concentration  (h). 
Hence  we  might  expect  that  the  curve  would  be  represented  by 
some  such  expression  as  a— chn  where  c  and  n  are  constants. 
This  assumption  may  be  tested  by  taking  any  two  corresponding 
sets  of  values  of  a  and  h  and  determining  the  values  of  c  and  n. 


rv]  Congress  of  Applied  Chemistry  65 

Using  these  values  of  c  and  n,  the  values  of  (a)  corresponding  to 
the  remaining  values  of  (h)  may  be  calculated  and  compared 
with  the  values  of  (a)  actually  determined.  Taking  the  first 
two  sets  of  values  of  (a)  and  (h)  for  determination  of  (c)  and  (n), 
the  calculation  is  as  follows: 

1.66  =  cxl2.8n 
2.69  =  cx22.7n 

2.69cxl2.8n  =  1.66cx22.7n 
1.62xl2.8n  =  22.7n 

Let  22.7  =  d,  12.8  =  k,  and  dn  =  m 

Then: 

d,  10log  m 

n=  logm  =  — — 
1.3560 

m 

and  n  =  klog  /  m   \      10log  1.62     10log  m  —  .2095 


1.62  /-     ioiogk  1.1072 


1.1072 

Hence  : 

10logm_10logm 
1.356       1.1072 


M  -t       ~<     A  •«   f~\ 

0log  m  =  1.1418 
1.356 


c 

8.556c  =  l.e6 
c=  .194 

Thus  the   expression  a  =  .194  h'842  satisfies  the  first  two  sets  of 
values  of  a  and  h. 


66  Original  Communications:  Eighth  International        [VOL. 

Calculation  of  the  remaining  values  of  (a),  using  these  values 
for  c  and  n,  gives  4.02  and  4.55,  while  the  values  actually  deter- 
mined were  3.97  and  4.59. 

||  Ether  solutions  of  nitroglycerin  as  already  noted  also  show 
association  of  the  molecules.  The  boiling-point  curve  is  of  the 
same  character  as  that  for  chloroform,  but  does  not  bend  toward 
the  x  axis  as  much.  Recalculation  of  the  values  for  (g)  as  before 
gives  the  following  values  of  h: 

a=  .86  h  =  9.75 

a  =  1.35  h  =  15.04 

a  =  2.29  h  =  25.65 

a  =  3.79  h  =  42.06 

Taking  the  extreme  values  of  a  and  h  and  calculating  as  before 
gives  the  values  c  =  .085  and  n  =  1.015.  Using  these  values  and 
calculating  from  the  expression  a  =  .085  h1'015  the  remaining 
values  of  (a),  give  the  values  1.33  and  2.29  as  against  values  actu- 
ally determined  of  1.35  and  2.29. 

Fina  ly  taking  the  results  with  methyl  alcohol  and  recalculating 
g  gives  as  values  for  h: 

a  =   .55  h  =  14.9 

a  =  1.21  h  =  28.0 

a  =  2.01  h=42.9 

a  =  2.56  h  =  52.7 

Calculation  from  the  extreme  values  of  a  and  h  gives  c  =  .0205 
and  n  =  1.218.  From  these  values  are  obtained  values  for  (a)  of 
1.19  and  2.00.  The  values  actually  found  were  1.21  and  2.01. 
Thus  the  expression  a  =  .0205  h  1<218  approximates  very  closely 
to  the  boiling-point  curve  of  this  solvent. 

The  above  calculations  seem  to  show  that  with  the  three  sol- 
vents dealt  with,  the  rise  in  boiling  point  follows  a  law  whose 
expression  is  of  the  form  a  =  chn  where  a  is  the  rise  in  boiling  point, 
h  the  percentage  composition  of  the  solution,  and  c  and  n  are 
constants.  The  agreement  between  calculated  and  determined 
values  of  a  for  all  three  solvents  is  again  shown  below: 


rv]  Congress  of  Applied  Chemistry  67 

a  calculated  a  determined 

4.02  3.97 

4.55  4.59 

1.33  1.35 

2.29  2.29 

1.19  1.21 

2.00  2.01 

The  writer  has  been  unable  to  find  any  rational  explanation  for 
this  expression,  nor  to  find  any  relation  between  the  values  of 
c  and  n  for  the  different  solvents,  and  it  is  of  course  possible  that 
the  formula  is  not  the  expression  of  any  law  at  all.  But  the  fact 
that  the  rise  in  boiling  point  of  three  different  solvents  should 
follow  so  closely  the  course  demanded  by  the  formula  makes  it 
seem  improbable  that  the  agreement  is  wholly  fanciful. 


SEPARATION     OF     NITROGLYCERIN     FROM     NITRO- 
SUBSTITUTION  COMPOUNDS 

BY  A.  L.  HYDE 

Bureau  of  Mines,  Pittsburgh,  Pa. 

The  separation  of  nitroglycerin  from  nitro  bodies  is  difficult 
because  practically  all  solvents  for  nitroglycerin  are  also  solvents 
for  the  different  nitro  bodies  and  vice  versa.  There  are,  however, 
considerable  differences  in  the  degree  of  solubility  in  different 
solvents  and  the  following  method  of  separation  depends  upon 
this  fact.  There  are  several  solvents  in  which  nitro  compounds  are 
more  soluble  than  is  nitroglycerin.  Among  these  are  acetone  and 
acetone  water  mixtures,  carbon  tetrachloride,  and  carbon  bisul- 
phide. There  are  also  several  solvents  which  dissolve  nitroglycerin 
more  readily  than  they  do  nitro  compounds.  Among  these  are 
ether,  formic  acid,  acetic  acid,  and  mixtures  of  these  acids  with 
water. 

It  is  evident  that  if  two  solvents  which  do  not  themselves  mix 
are  shaken  together  with  a  mixture  of  nitroglycerin  and  a  nitro- 
compound  there  will  be  a  partial  separation  of  the  mixture  provided 
that  in  one  of  these  solvents  nitroglycerin  is  more  soluble  than 
the  nitro  compound  and  that  in  the  other  solvent  the  nitro  com- 
pound is  more  soluble  than  nitroglycerin.  Hence  the  conditions 
that  two  solvents  shall  be  available  for  this  method  of  separation 
are  that  they  shall  be  nearly  insoluble  in  each  other  and  that  one 
shall  dissolve  nitroglycerin  more  readily  than  it  dissolves  nitro 
compounds,  while  the  other  dissolves  nitro  compounds  more 
readily  than  it  dissolves  nitroglycerin. 

The  solvents  mentioned  above  may  be  examined  with  a  view 
of  determining  how  far  they  satisfy  these  conditions.  Acetone 
mixes  with  almost  all  organic  solvents  including  ether,  formic  acid 
and  acetic  acid.  This  solvent  therefore  is  not  available.  Carbon 
tetrachloride  mixes  with  ether  and  acetic  acid  but  only  slightly 
with  formic  acid.  If  other  conditions  were  favorable,  carbon 
tetrachloride  and  formic  acid  water  mixtures  might  therefore  be 
used  for  the  separation.  Carbon  bisulphide  mixes  with  ether, 

69 


70  Original  Communications:  Eighth  International        [VOL. 

but  only  slightly  with  acetic  or  formic  acids.  It  therefore  appears 
that  carbon  bisulphide  and  either  acetic  or  formic  acid  water 
mixtures  would  be  available. 

Preliminary  experiments  with  all  these  solvents  showed  that 
a  single  shaking  with  any  pair  of  solvents  gives  only  a  very  in- 
complete separation  of  nitroglycerin  from  nitro  compounds.  A 
sort  of  fractional  separation  was  then  attempted.  The  first  two 
solvents  tried  were  carbon  tetrachloride  and  formic  acid.  A 
number  of  experiments  showed  that  a  mixture  of  65  parts  of  formic 
acid  to  35  parts  of  water  by  volume  was  the  most  promising. 
The  method  used  was  as  follows:  A  mixture  containing  known 
quantities  of  nitroglycerin  and  liquid  trinitrotoluene  was  poured 
into  a  separating  flask  and  the  small  remainder  in  the  beaker 
washed  in  with  a  definite  volume  of  carbon  tetrachloride.  A 
definite  volume  of  formic  acid  water  mixture  was  then  added  and 
the  whole  shaken  in  the  separating  flask.  After  separation  of 
the  liquids,  the  carbon  tetrachloride  was  run  into  a  beaker.  A 
second  portion  of  carbon  tetrachloride  was  added  to  the  formic 
acid  mixture  and  shaken  with  it  and  run  into  a  second  beaker. 
A  third  portion  of  carbon  tetrachloride  was  added  and  run  into 
a  third  beaker.  The  formic  acid  mixture  was  then  removed  from 
the  flask  and  placed  in  a  beaker.  A  second  portion  of  formic 
acid  mixture  was  then  shaken  with  the  three  portions  of  carbon 
tetrachloride  in  turn  and  finally  placed  in  another  beaker.  A 
third  portion  of  formic  acid  mixture  was  treated  in  the  same  way. 
The  three  portions  of  carbon  tetrachloride  were  then  poured  to- 
gether and  the  solvent  evaporated  off  on  the  steam  bath  and  the 
residue  consisting  of  trinitrotoluene  and  some  nitroglycerin 
weighed.  Sulphuric  acid  was  then  added  to  this  residue  and  the 
amount  of  nitroglycerin  present  determined  on  the  nitrometer. 

A  number  of  mixtures  of  trinitrotoluene  and  nitroglycerin 
were  treated  in  this  manner  using  different  proportions  of  the 
two  solvents,  but  the  results  were  not  very  promising.  One  single 
result  may  be  given.  A  mixture  consisting  of  1.790  grams  of 
liquid  trinitrotoluene  and  4.713  grams  of  nitroglycerin  was  treated 
as  above,  each  portion  of  formic  acid  mixture  used  being  30  cc. 
and  each  portion  of  carbon  tetrachloride  45  cc.  The  residue  after 
evaporation  of  the  carbon  tetrachloride  weighed  1.673  grams  or 


iv]  Congress  of  Applied  Chemistry  71 

about  94  per  cent  of  the  weight  of  nitrotoluene  originally  present. 
A  determination  of  the  NO  given  off  in  the  nitrometer,  however, 
showed  that  this  still  contained  about  .4  gram  of  nitroglycerin. 
This  was  of  course  far  too  much  for  hope  of  quantitative  results. 
Also  there  seemed  to  have  been  some  action  between  the  carbon 
tetrachlorid  and  the  nitrotoluene,  as  upon  adding  sulphuric 
acid  to  the  residue  an  odor  of  chlorine  was  noticeable.  Still  another 
difficulty  is  the  high  boiling  point  of  carbon  tetrachloride  and 
the  danger  of  losing  nitrotoluene  during  the  evaporation.  These 
two  solvents  were  therefore  abandoned. 

The  method  of  fractional  separation  as  above  described  was 
next  tried  with  the  solvents  carbon  bisulphide  and  acetic  acid 
water  mixtures.  Several  different  mixtures  of  acetic  acid  and 
water  were  tried  and  the  one  finally  chosen  as  promising  best 
results  was  a  mixture  containing  65  parts  acetic  acid  (99.5  per 
cent  pure)  and  35  parts  water  by  volume.  This  mixture  was 
used  with  freshly  distilled  carbon  bisulphide  in  the  proportions 
of  22.5  cc.  acetic  acid  mixture  to  50  cc.  of  carbon  bisulphide  and 
the  fractionation  carried  on  as  above  described  using  three  por- 
tions of  each  solvent.  A  mixture  consisting  of  1.007  grams  of 
liquid  trinitrotoluene  and  1.743  grams  of  nitroglycerin  treated 
in  this  way  gave  a  residue  after  evaporation  of  the  carbon  bisul- 
phide which  weighed  .973  gram.  Determination  in  the  nitro- 
meter showed  that  this  residue  contained  about  .2  gram  of  nitro- 
glycerin. 

This  separation  was  still  too  incomplete  for  quantitative  pur- 
poses and  fractionation  of  another  sample  was  carried  one  step 
further,  using  four  portions  each  of  acetic  acid  mixture  and  carbon 
bisulphide  in  the  same  proportions  as  before.  In  this  way  a 
mixture  containing  1.515  grams  of  liquid  trinitrotoluol  and  1.915 
grams  of  nitroglycerin  gave  a  residue  weighing  1.439  grams 
containing  about  .15  grams  of  nitroglycerin.  Another  mixture 
containing  .487  gram  of  liquid  trinitrotoluene  and  3.076  grams 
of  nitroglycerin  treated  in  the  same  way  gave  a  residue  weighing 
.599  gram.  It  was  thought  that  results  more  nearly  quantitative 
might  be  obtained  by  correcting  for  the  amount  of  nitroglycerin 
remaining  in  the  carbon  bisulphide  and  the  nitrotoluene  remaining 
in  the  acetic  acid  mixture.  With  this  end  in  view  several  separa- 


72  Original  Communications:  Eighth  International        [VOL. 

tions  were  made  using  three  portions  each  of  carbon  bisulphide 
and  acetic  acid  water  mixture.  The  results,  however,  showed 
rather  large  variations.  They  were  as  follows:  A  mixture  con- 
taining 1.527  grams  of  liquid  trinitrotoluene  and  2.168  grams  of 
nitroglycerin  gave  a  residue  after  evaporation  of  the  carbon  disul- 
phide  weighing  1.475  grams.  A  mixture  containing  .509  gram 
of  liquid  trinitrotoluene  and  3.484  grams  of  nitroglycerin  gave  a 
residue  weighing  .695  gram.  A  mixture  containing  1.083  grams 
of  crystalline  dinitrotoluene  and  2.094  grams  of  nitroglycerin  gave 
a  residue  weighing  1.223  grams.  A  mixt^aie  containing  .308  gram 
of  crystalline  dinitrotoluene  and  1.9301  grams  of  nitroglycerin 
gave  a  residue  weighing  .451  gram.  A  mixture  containing  .751 
gram  of  paranitrotoluene  and  2.111  grams  of  nitroglycerin  gave 
a  residue  weighing  .753  gram.  A  mixture  containing  1.142  grams 
of  paranitrotoluene  and  2.416  grams  of  nitroglycerin  gave  a  residue 
weighing  1.398  grams.  If  it  is  assumed  that  under  the  conditions 
of  the  separation  one-tenth  of  the  nitroglycerin  originally  present 
remains  in  the  carbon  bisulphide  while  from  80  to  90  per  cent  of 
the  nitrotoluene  is  found  there,  these  results  are  much  more 
concordant  than  they  appear  at  first  glance.  Even  with  this 
correction,  however,  the  results  show  that  this  method  is  available 
only  in  a  rough  way.  Carbon  bisulphide  and  acetic  acid  are  not 
absolutely  insoluble  in  each  other  and  most  of  the  variations  are 
probably  due  to  this  fact  together  with  the  difficulty  of  carrying 
on  so  many  manipulations  with  the  different  portions  of  solvents 
in  a  uniform  manner.  The  slight  volatility  of  paranitrotoluene 
also  plays  some  part  in  the  last  two  results.  This  method  of 
procedure  was  abandoned  for  the  one  which  follows. 

It  was  thought  that  it  might  be  possible  to  remove  practically 
all  the  nitroglycerin  from  the  nitro  body  and  still  leave  a  fairly 
definite  fraction  of  the  latter  in  the  carbon  bisulphide.  This 
proved  to  be  the  case.  A  preliminary  separation  of  a  mixture 
containing  1.631  grams  of  liquid  trinitrotoluene  and  2.078  grams 
of  nitroglycerin  with  75  cc.  of  carbon  bisulphide  shaken  with  4 
portions  of  30  cc.  each  of  acetic  acid  water  mixture  gave  in  the 
carbon  bisulphide  about  one-third  of  the  nitrotoluene  containing 
less  than  10  mg.  of  nitroglycerin.  A  uniform  method  of  procedure 
was  then  adopted  and  the  fraction  of  different  nitro  compounds 


iv]  Congress  of  Applied  Chemistry  73 

left  in  the  carbon  bisulphide  determined.  The  results  show  a 
uniformity  sufficient  for  a  fairly  accurate  determination  of  the 
different  nitro  compounds  in  the  presence  of  nitroglycerin. 

The  following  method  of  procedure  was  the  one  adopted.  A 
mixture  of  65  parts  acetic  acid  (99.5  per  cent  pure)  and  35  parts 
water  by  volume  was  made  up.  Carbon  bisulphide  was  freshly 
distilled.  The  mixture  of  nitroglycerin  and  nitro  compound  in  a 
small  beaker  was  poured  into  a  medium-sized  separating  flask 
and  the  remaining  contents  of  the  beaker  washed  into  the  flask 
with  30  cc.  of  the  acetic  acid  water  mixture.  75  cc.  of  carbon 
bisulphide  was  added  to  the  flask  and  the  whole  shaken  and  then 
allowed  to  separate.  The  carbon  bisulphide  was  then  drawn  off 
into  a  small  Erlenmeyer  flask  and  the  acetic  acid  solution  poured 
into  a  beaker.  The  carbon  bisulphide  was  poured  back  into  the 
separating  flask  and  shaken  with  a  second  30-cc.  portion  of  acetic 
acid  mixture.  This  was  repeated  with  two  more  portions  of  acid 
mixture  so  that  the  75  cc.  of  carbon  bisulphide  had  finally  been 
treated  with  120  cc.  of  acetic  acid  mixture  in  30  cc.  portions. 
Finally  the  carbon  bisulphide  was  washed  with  one  75-cc.  portion 
of  water  to  remove  the  acetic  acid  taken  up  and  afterwards  run 
into  a  small  beaker.  It  was  then  ready  for  the  evaporation. 

Since  some  of  the  nitro  compounds  are  slightly  volatile  at  the 
boiling  point  of  carbon  bisulphide,  a  special  method  of  evaporation 
of  the  solvent  was  used.  A  bell  jar  having  a  hole  in  the  top  and 
one  in  the  side  was  placed  over  the  beaker  containing  the  carbon 
bisulphide  solution.  A  rubber  stopper  through  which  was  passed 
a  glass  tube  was  placed  in  the  top  hole.  The  glass  tube  reached 
down  to  within  about  an  inch  of  the  top  of  the  liquid  in  the  beaker. 
A  rubber  tube  was  connected  to  the  side  opening  of  the  bell  jar 
to  carry  off  the  vapors  of  carbon  bisulphide.  Air,  dried  by  passing 
through  two  calcium  chloride  tubes,  was  blown  down  through  the 
glass  tube  upon  the  surface  of  the  liquid.  The  liquid  immediately 
became  so  cold  that  the  loss  of  nitrotoluene  by  evaporation  was 
very  slight.  Immediately  after  the  carbon  bisulphide  was  evapo- 
rated which  could  be  determined  by  the  melting  of  the  few  very 
fine  particles  of  ice  present,  the  beaker  was  placed  in  a  desiccator 
over  sulphuric  acid  and  weighed  after  12  hours.  A  test  to  deter- 
mine the  evaporation  of  the  nitro  compound  when  using  this 


74  Original  Communications:  Eighth  International        [VOL. 

apparatus  was  made.  The  loss  from  2.382  grams  of  orthonitro- 
toluene  (the  most  volatile  of  the  nitrotoluenes)  was  7  mg.  in 
evaporating  50  cc.  of  carbon  bisulphide  from  it. 

The  following  tables  show  the  results  when  using  the  above 
method. 

Per  cent  of 

Mixture  treated  Recovered  from  original  nitro  com- 

Orthonitrotoluene        Nitroglycerin  CS«  solution        pound  recovered 

2.475  grams  1.841  grams  1.889  grams  76.4 

1.069  grams  4.099  grams  .790  gram  73.9 

1.281  grams  2.705  grams  .955  gram  74.6 
Average  percentage  of  nitro  compound  recovered,  75  per  cent. 

Per  cent  of 

Liquid  Recovered  from  original  nitro  com- 

Dinitrotoluene  Nitroglycerin  CSi  solution      pound  recovered 

2.144  grams  1.566  grams  .782  gram  36.5 

1.014  grams  3.902  grams  .357  gram  35.2 

1.169  grams  3.741  grams  .415  gram  35.5 

Average  percentage  of  nitro  compound  recovered,  35.7  per  cent. 

Mixture  treated  Per  cent  of 

Liquid  Recovered  from  original  nitro  corn- 

Trinitrotoluene  Nitroglycerin  CS«  solution      pound  recovered 

2.033  grams  1.886  grams  .574  gram  28.2 

1.236  grams  2.792  grams  .340  gram  27.5 

1.118  grams  4.625  grams  .296  gram  26.5 

Average  percentage  of  nitro  compound  recovered,  27.4  per  cent. 

Per  cent  of 

Dinitrotoluene  Recovered  from  original  nitro  com- 

M.P.66°-68°  C.          Nitroglycerin  CSs  solution      pound  recovered 

1.077  grams  3.196  grams  .425  gram  39.5 

1.807  grams  1.472  grams  .758  gram  41.9 

1.606  grams  3.035  grams  .647  gram  40.3 

Average  percentage  of  nitro  compound  recovered,  40.6  per  cent. 

Per  cent  of 

Recovered  from  original  nitro  com- 
Paranitro toluene          Nitroglycerin  CSZ  solution      pound  recovered 

2.282  grams  1.444  grams  1.756  grams  77.0 
1.008  grams           3.425  grams               .788  gram  78.1 
1.615  grams           3.074  grams             1.227  grams  76.0 

Average  percentage  of  nitro  compound  recovered,  77.0  per  cent. 


rv]  Congress  of  Applied  Chemistry  75 

Per  cent  of 

Dinitrotoluene  Recovered  from  original  nitro  com- 

M.P.  48°  C.  Nitroglycerin  CS»  solution       pound  recovered 

2.192  grams  1.754  grams  .893  gram  40.7 

1.073  grams  3.752  grams  .421  gram  39.2 

1.504  grams  3.476  grams  .584  gram  38.8 

Average  percentage  of  nitro  compound  recovered,  39.6  per  cent. 
These  results  show  that  while  no  very  great  exactness  can  be 
claimed  for  the  method  as  a  quantitative  one,  still  it  is  sufficiently 
accurate  for  practical  purposes  in  many  cases.  The  mixtures 
tried  represent  a  rather  wide  range  in  the  proportion  of  nitrogly- 
cerin  to  nitro  compound,  yet  the  error  involved  in  the  determination 
of  a  nitro  compound  by  assuming  the  average  percentage  in  each 
case  would  not  be  excessive  for  practical  purposes. 

The  average  amount  of  each  nitro  compound  recovered  by  the 
above  treatment  is  given  below. 

Orthonitrotoluene  75.0  per  cent 

Liquid  dinitrotoluene  35.7  per  cent 
Liquid  trinitrotoluene  27.4  per  cent 
Dinitrotoluene 

M.  P.  66°-68°C.       40.6  per  cent 
Paranitrotoluene  77.0  per  cent 

Dinitrotoluene 

M.  P.  48°  C.  39.6  per  cent 

Assuming  the  above  averages  as  the  basis  of  calculation,  a 
determination  of  the  nitro  compound  in  the  18  mixtures  shown 
above  would  give  percentages  of  the  amount  actually  present  as 
shown  in  the  following  table.  The  mixtures  are  numbered  in  the 
same  order  as  given  above. 

Mixture  1-101.8  per  cent  Mixture  10-  97.3  per  cent 

Mixture  2-  98.5  per  cent  Mixture  11-103.2  per  cent 

Mixture  3-  99.4  per  cent  Mixture  12-  99.2  per  cent 

Mixture  4-102.2  per  cent  Mixture  13-100.0  per  cent 

Mixture  5-  98.6  per  cent  Mixture  14-101.4  per  cent 

Mixture  6-  99.4  per  cent  Mixture  15-  98.7  per  cent 

Mixture  7-102.9  per  cent  Mixture  16-102.7  per  cent 

Mixture  8-100.4  per  cent  Mixture  17-  98.9  per  cent 

Mixture  9-  96.7  per  cent  Mixture  18-  97.9  per  cent 


76  Original  Communications:  Eighth  International 

There  are  several  errors  involved  in  this  method  which  prevent 
its  being  exactly  quantitative.  In  the  first  place,  the  final  product 
weighed  is  not  the  pure  nitro-compound  but  contains  in  every 
case  a  few  milligrams  of  nitroglycerin,  the  exact  amount  depending 
upon  the  quantity  originally  present  in  the  mixture.  The  separa- 
tion could  of  course  be  carried  further,  but  in  that  case  the  frac- 
tion of  nitro-compound  recovered  would  be  decreased  and  all 
errors  of  manipulation  would  consequently  be  multiplied  by  a 
larger  factor.  Again,  the  solubilities  of  nitroglycerin  and  the 
nitro-compound  in  each  other  play  a  part  which  varies  somewhat 
with  different  proportions.  With  the  more  volatile  nitro-com- 
pounds  there  is  also  some  error  involved  in  evaporating  off  the 
solvent  and  drying  in  the  desiccator.  Finally  there  are  the  errors 
which  are  unavoidable  in  the  separation  of  two  liquids  by  means 
of  a  separating  flask,  such  as  solubility  of  one  in  the  other,  evapora- 
tion of  the  liquids  during  manipulation,  etc. 

Keeping  in  mind  these  limitations,  it  seems  probable  that  the 
method  may  have  a  fairly  wide  application.  Qualitative  tests 
upon  the  nitronaphthalenes  show  that  it  may  be  applied  to  mix- 
tures of  these  substances  with  nitroglycerin  and  probably  to  most 
other  nitro-compounds.  The  great  difference  between  the  fractions 
of  mononitro-compounds  and  dinitro-compounds  recovered  from 
the  CS2  solution  in  the  above  mixtures  also  indicates  that  a  separa- 
tion of  these  compounds  might  be  possible  by  varying  the  relative 
proportions  of  the  solvents. 

It  must  be  remembered  that  the  method  is  strictly  empirical 
and  the  manipulations  must  be  carried  out  in  a  definite  manner 
in  order  to  obtain  results  even  approximately  quantitative. 


Abstract 

HYDROLYSIS    OF    TRI-NITRO-ANISOL    BY 
ALKALIES    AND     WATER 

BT  WALTER  E.  MASLAND  AND  FIN  SPARRB 
Wilmington,  Delaware 

Very  little  information  is  to  be  found  in  chemical  literature  in 
regard  to  the  stability  of  tri-nitro-anisol,  the  methyl  ester  of  tri- 
nitro-phenol  or  picric  acid,  in  the  presence  of  alkalies  and  water. 
This  question  being  of  considerable  importance  in  connection 
with  the  possible  application  of  this  material  in  the  explosives 
industry,  an  investigation  of  the  stability  was  undertaken. 

Pure  tri-nitro-anisol  was  prepared  by  the  nitration  of  mono- 
nitro-anisol  with  a  strong  mixture  of  sulphuric  and  nitric  acids. 
The  purity  of  the  mono-and  tri-nitro  derivatives  was  proved  by 
determinations  of  molecular  weight,  percentage  of  methoxyl 
radicals,  etc.  The  following  information  was  obtained  from  an 
investigation  of  the  hydrolyzing  action  of  water  and  alkalies: 

1.  Alkaline    carbonate   solutions,    slowly   in   the    cold,    more 
rapidly  when  hot,  hydrolyze  the  ester  with  formation  of  alkali 
picrates. 

2.  Pure  hot  water  slowly  hydrolyzes  the  ester  with  the  forma- 
tion of  picric  acid. 

3.  Pure  cold  water  appears  to  have  the  same  but  much  weaker 
hydrolyzing  action. 

The  identity  of  the  products  of  hydrolysis  was  shown  by  ana- 
lytical tests,  molecular  weight  determinations,  etc. 


77 


A  PLEA  FOR  IMPROVEMENT  IN  THE  METHODS  OF 
CHEMICAL  TESTING  OF  MINING  EXPLOSIVES 

BY  JAMES  Mom,  D.Sc.,  M.A. 

Chemical  Laboratory  of  the  Department  of  Mines,  Union  of  South 
Africa  (Johannesburg) 

The  subject  of  the  testing  of  explosives  divides  itself,  on  the 
chemical  side,  into  (1)  the  stability  or  heat-test,  and  (2)  proximate 
analysis. 

Of  the  known  stability  tests,  I  shall  deal  only  with  the  official 
heat-test  of  the  British  Home  Office,  as  being  the  only  one  capable 
of  giving  a  result  in  a  reasonable  time — which  is  a  fundamental 
requirement  of  an  analytical  laboratory. 

This  heat-test  consists,  as  is  well  known,  in  observing  the 
time  required  to  produce  a  standard  iodine-stain  on  iodised 
starch-paper  (moistened  in  a  thin  line  by  50%  glycerol  solution) 
by  means  of  the  traces  of  nitric  peroxide  evolved  when  explosives 
are  heated  to  such  temperatures  as  70  to  80°C.  The  test  was 
invented  (about  the  year  1875,  I  believe)  to  deal  with  nitro- 
glycerine and  cordite,  and  acts  well  with  these  and  similar  explo- 
sives (i.  e.,  with  an  experimental  error  of  5%  or  so);  but  my  ex- 
perience of  it  with  mining  explosives,  for  which  the  test  is 
prescribed  by  most  of  the  Governments  of  the  world,  is  quite 
unsatisfactory. 

The  defects  are  of  two  kinds:  (1)  those  due  to  the  nature  of 
the  reagent,  and  (2)  those  caused  by  ingredients  of  the  explosives 
tested  or  by  impurities  in  the  French-chalk  used  to  reduce  the 
sample  to  a  powder.  In  regard  to  the  first  kind  of  defect,  the 
main  difficulty  is  the  volatility  of  the  iodine  or  the  sensitiveness 
to  heat  of  the  coloured  compound  with  starch,  in  consequence 
of  which  the  results  are  liable  to  variation  whenever  slight  changes 
of  the  depth  of  immersion  in  the  water-bath,  or  of  the  precise 
position  of  the  test-paper  in  the  tube,  happen  to  occur.  The 
test  itself  is  of  course  nowadays  looked  on  as  probably  the  least 
sensitive  of  all  the  known  tests  for  nitrous  fumes,  and  would 
deserve,  were  it  not  for  an  advantage  to  be  discussed  later  on,  to 

79 


80  Original  Communications:  Eighth  International        [VOL. 

be  relegated  to  the  oblivion  of  University  lectures,  and  replaced 
by  any  of  the  good  organic  reagents  for  nitrous  acid,  such  as 
indole,  ra-phenylenediamine,  or  Ilosvay's  reagent. 

Of  the  defects  due  to  the  nature  of  the  explosives  tested,  it  may 
be  said  that  all  are  due  to  the  presence  of  some  volatile  substance 
wh  ch  is  capable  of  combining  either  with  iodine  or  with  nitric 
peroxide,  and  so  spoiling  the  test.  The  best-known  case  is  that 
of  mercuric  chloride,  the  presence  of  which,  even  in  quantity 
so  little  as  1  in  50,000,  almost  entirely  masks  the  action  of  the 
test-paper. 

Even  water,  however,  when  present  to  the  extent  of  over  1% 
in  gelignite  for  example,  makes  the  test  insensitive  by  50%  or 
so.  This  is  due  to  the  reaction  between  steam  and  NO2  (H^O-f- 
3N02  =  2HN03-{-NO)  whereby  the  greater  part  of  the  nitrous 
fumes  are  rendered  inert  by  oxidation  to  (dilute)  nitric  acid :  (this 
occurs  also  in  the  cold,  but  to  a  smaller  extent) . 

It  may  of  course  be  said  that  it  is  easy  to  dry  the  explosive  before 
heat-testing.  This  can  be  done  in  a  sulphuric  acid  vacuum  in  24 
hours,  if  the  sample  is  cut  into  thin  slices.  The  desiccator  must 
be  kept  in  the  dark,  and  not  used  too  often,  else  fumes  from  ab- 
sorbed nitroglycerine  vapour  will  vitiate  the  test.  As  a  rule,  how- 
ever, heat-tests  are  urgent  work  and  cannot  be  postponed  for  a 
day  or  two. 

A  more  serious  factor  is  the  use  of  pinewood  sawdust  as  absorbent 
in  dynamites,  etc.  This  on  heating  evolves  terpenes  which  absorb 
any  N02  that  is  being  formed.  Thus,  a  blasting-gelatine  giving 
a  heat-test  of  15  minutes,  will,  on  incorporation  with  some  of  this 
sawdust,  give  a  test  of  30  minutes  as  a  rule.  To  my  mind,  there 
is  no  moral  or  legal  distinction  between  this  use  of  terpenes  to 
mask  the  official  test  and  the  use  of  mercury — which  has  already 
brought  many  dynamite-factories  into  conflict  with  their  Govern- 
ments. 

While  I  am  on  this  branch  of  the  subject,  I  should  like  to  say 
that  I  think  that  the  official  procedure  for  testing  'Dynamite  F 
(Kieselguhr  dynamite)  by  extraction  with  water,  is  perfectly 
useless.  Nitroglycerine  when  properly  washed,  is  a  perfectly 
stable  substance,  and  will  give  a  very  long  heat-test;  and  so  it 
does  when  extracted  from  these  dynamite  samples,  even  when 


iv]  Congress  of  Applied  Chemistry  81 

the  samples,  tested  directly  as  if  they  were  '  'Dynamite  II,"  give 
very  poor  tests. 

I  shall  now  mention  a  few  factors  which  act  in  the  opposite 
direction,  and  shorten  the  test-period.  The  first  of  these  is  ex- 
posure to  bright  light.  This  is  very  marked  in  such  a  high-lying 
and  sunny  country  as  South  Africa;  thus,  one  minute's  exposure 
of  an  explosive  to  the  sun  will  ruin  its  heat-test,  and  has  even  been 
known  to  lead  to  explosion.  The  second  is  the  presence  of  very 
finely-divided  carbon  in  grey  specimens  of  French  chalk.  This 
acts  catalytically  on  the  explosive  and  lowers  the  heat-test.  It 
is  liable  to  be  produced  when  commercial  French  chalk  (which 
contains  an  objectionable  scented  impurity)  is  dried  at  too  high 
a  temperature.  A  third  and  more  doubtful  factor  is  low  atmos- 
pheric pressure:  certainly  tests  done  in  Johannesburg  at  24J 
inches  barometer  seem  to  give  shorter  periods  than  tests  on  the 
same  samples  done  at  the  sea-coast.  This  is  hard  to  explain,  since 
the  reaction-velocity  ought  to  depend  on  temperature  alone. 

I  have  suggested  that  the  official  iodide  test  should  be  replaced 
by  ore  of  the  organic  tests,  but  a  strong  factor  in  favour  of  the 
old  test  is  the  fact  that  its  time  of  appearance  is  much  more  definite 
than  that  of  the  organic  tests.  This  is  due  to  a  cyclic  process 
involving  the  constant  liberation  of  nitric  oxide  (NO)  and  its 
re-oxidation  to  N02,  so  that  a  small  quantity  of  nitrous  fumes 
liberates  a  considerable  quantity  of  iodine.  The  reactions  are: 

(1)  2  N02+H20  (on  wet  part  of  paper)  -HN03+HNO2. 

(2)  HNCM  HN02+KI  =  KN03+H20+NO+I. 

(3)  NO+i02  =  N02  (assuming  excess  of  air). 


Thus  half  the  original  N02  is  regenerated,  and  the  whole  process 
can  therefore  be  represented  by  the  single  equation: 

(4)  2  NO.+2KI+02  =  2KN03+I2. 

In  consequence  of  this,  the  iodine  colour  deepens  quite  rapidly 
very  soon  after  the  first  trace  makes  its  appearance:  whereas  in 
the  organic  tests,  the  deepening  of  colour  is  progressive  all  through, 
and  constant  comparison  with  a  standard  would  be  necessary. 

I  have  however  got  good  results  with  a  test  liquid  made  of 
equal  parts  of  glycerol  and  Ilosvay's  reagent  (0.6  gram  of  sul- 


82  Original  Communications:  Eighth  International        [VOL. 

phanilic  acid  and  0.5  gram  of  alphanaphthylamine  dissolved 
together  in  100  cc.  of  water  with  a  few  drops  of  acetic  acid). 
This  is  approximately  seven  times  more  sensitive  than  KI  towards 
nitrous  fumes,  and  is  not  affected  by  mercury  or  terpenes  or  mois- 
ture. To  bring  it  down  to  about  the  same  sensitiveness  as  the 
official  test,  a  lower  temperature  of  the  heat-test  water-bath  may 
be  used  (approximately 45°C.  instead  of  71°),  and  an  arbitrary 
pink  standard,  similar  to  pink  blotting-paper  for  example,  may 
be  chosen  to  work  to.  A  solution  of  pure  indole,  say  1  in  1,000  of 
50%  glycerine,  gives  similar  results. 

Guttmann's  test  is  useless  for  moist  explosives,  because  the 
green  colour  is  not  produced  unless  the  sulphuric  acid  remains 
undiluted,  which  is  not  the  case  in  practice. 

To  summarise  this  branch  of  the  subject,  the  official  iodide 
test  does  not  work  well  with  mining  explosives,  except  blasting- 
gelatine  and  Kieselguhr  dynamite. 

The  second  division  of  my  remarks  deals  with  the  question  of 
proximate  analysis  of  complex  nitroglycerine  explosives,  wherein 
I  have  met  with  sources  of  serious  error  not  mentioned  in  the 
current  works  on  the  subject.  Take  the  case  of  that  familiar 
explosive  gelignite.  This  is  a  mixture  of  a  'thin'  blasting-gelatine 
with  a  dope  composed  of  fine  sawdust  and  saltpetre.  When  the 
analysis  is  commenced  (as  usual)  by  drying  in  a  vacuum  over 
sulphuric  acid,  a  trace  of  the  nitroglyce  ine  is  lost  by  volatilisa- 
tion unless  one  stops  short  of  the  stage  of  complete  drying,  namely 
by  giving  24  hours  for  the  process.  In  the  second  stage,  viz., 
ether  extraction  by  the  Soxhlet  or  other  method,  I  find  that  serious 
error  is  caused  by  extraction  of  fatty  and  resinous  matter  from 
the  sawdust.  This  may  be  only  say  J%  in  the  case  of  gelignite, 
but  may  be  several  parts  per  cent,  in  the  case  of  'Dynamite  II.' 

The  residue  is  a  mixture  of  nitrocotton,  sawdust  and  saltpetre, 
and  may  be  worked  up  in  either  of  two  ways,  both  of  which  are 
subject  to  unavoidable  error.  The  usual  method  is  that  o!  boiling 
with  water  (after  moistening  with  alcohol  to  cause  the  sample  to 
sink).  This  is  intended  to  remove  saltpetre  and  soluble  alkali, 
but  also  generally  removes  some  soluble  constituent  (sugar, 
saponin,  etc.)  from  the  wood-pulp,  so  that  a  determination  by 
difference  is  too  high,  even  if  correct  allowance  is  made  for  any 


iv]  Congress  of  Applied  Chemistry  83 

alkali  after  titration.  My  attempts  to  improve  on  this  by  pre- 
cipitation w'th  'nitron'  (phenylimino-diphenyltriazole)  gave  results 
generally  £%  too  low;  and  in  South  Africa,  where  sodium  nitrate 
is  permitted  in  place  of  saltpetre,  the  evaporation  methods  are 
practically  impossible.  This  method  is  finished  off  by  extracting 
the  nitrocotton  with  ether-alcohol  or  ether-acetone,  and  finally, 
the  residue  of  the  wood  is  examined  for  insoluble  alkali  (such  as 
calcium-carbonate)  by  t'.tration. 

The  alternative  procedure  is  to  remove  the  nitrocotton  first  by 
the  above  solvent-mixtures,  and,  as  everyone  knows,  great  manip- 
ulative difficulties  are  met  with  in  filtering  this  viscous  and  volatile 
mixture.  For  special  work  where  accurate  values  of  the  nitro- 
cotton content  alone  are  required,  I  prefer  to  measure  the  bulk  of 
the  mixture  (made  by  several  hours'  shaking  in  a  closed  and 
graduated  vessel^,  allow  to  settle,  and  decant  and  evaporate  the 
upper  half  of  the  extract,  allowing  for  the  bulky  insoluble  at  about 
ha]f  its  apparent  volume. 

The  residue  of  sawdust  and  saltpetre  can  now  be  separated  by 
cold  water  quite  satisfactorily,  whereas  in  presence  of  nitrocotton 
it  is  necessary  to  boil  with  water  in  order  to  get  at  the  saltpetre. 

The  use  of  sodium  monosulphide  for  dissolving  nitrocotton 
is  only  possible  where  wood-pulp  is  absent,  since  it  apparently 
dissolves  every  constituent  of  wood  except  the  cellulose,  and  even 
the  latter  absorbs  sodium  quite  strongly. 

Another  'thorn  in  the  flesh'  of  the  explosives-analyst  is  the 
recent  introduction  of  substitutes  for  part  of  the  nitroglycerine  in 
explosives,  such  as  trinitrotoluene.  Towards  solvents  these 
substances  behave  e:  actly  like  nitroglycerine,  and  the  only  possible 
method  of  analysis  appears  to  consist  in  evaporating  the  ether- 
extract  and  determining  the  amount  of  nitroglycerine  by  the 
nitrometer.  (Trinitrotoluene  does  not  react  with  sulphuric  acid 
and  mercury).  Owing  to  volatilisation  of  nitroglycerine  and 
other  causes,  this  gives  very  poor  results.  Other  methods  of 
determining  nitrogen  are  useless  because  both  trinitrotoluene  and 
nitroglycerine  contain  the  same  percentage  of  nitrogen. 


DETONATOR  TROUBLES  EXPERIENCED  IN  THE 
CONSTRUCTION  OF  THE  ISTHMIAN  CANAL 

BY  ARTHUR  LEE  ROBINSON 
Gorgona,  Panama  Canal  Zone 

A  preliminary  survey  of  the  work  to  be  performed  in  the  con- 
struction of  the  Isthmian  Canal  would  have  led  the  majority 
of  engineers  to  presuppose  that  the  ordinary  commercial  products 
of  the  United  States  and  Europe  would  meet  all  the  requirements 
and  necessities  of  such  a  service.  Yet  the  actual  construction 
of  the  Isthmian  Canal  has  called  for  improvements  in  many 
classes  of  machinery  and  the  special  manufacture  of  many  other 
products  in  order  to  meet  the  exigencies  of  this  service.  After 
the  years  of  mining  operations  in  all  countries  of  the  world  it 
would  be  no  more  than  natural  to  presume  that  the  usual  methods 
and  materials  employed  at  home  and  abroad  for  blasting  purposes 
would  fully  answer  all  requirements  of  the  apparently  simple 
work  of  breaking  ground  for  excavation  by  steam  shovels  on  this 
Isthmian  Canal.  However,  troubles  were  encountered  with 
detonators  of  such  a  serious  nature  as  to  require  changes  in  their 
structu  e  by  manufacturers  and  also  changes  in  the  usual  method 
of  firing.  These  troubles  originated  from  two  distinct  sources 
and  will  be  discussed  in  this  paper  under  the  following  heads: 
First,  The  Absorption  of  Moisture  by  Detonators;  Second,  The 
Nonuniformity  of  Detonator  Current  Explosive  Values. 

THE   ABSORPTION   OF   MOISTURE   BY   DETONATORS 

While  the  United  States  Government  formally  entered  upon 
the  work  of  Canal  construction  in  May,  1904,  comparatively 
little  excavation  was  begun  or  accomplished  during  that  year. 
Among  the  early  requisitions  for  material  and  supplies  was  an 
order  for  500,000  pounds  of  dynamite,  which  material  after 
receipt  was  found  sufficient  to  last  through  the  years  1904  and 
1905.  In  1906,  1,400,000  pounds  was  purchased  and  used. 
Throughout  the  two  and  one-half  years  of  operation  in  1904, 

85 


86  Original  Communications:  Eighth  International        [VOL. 

1905  and  1906  the  construction  work  required  comparatively 
light  surface  mining  and  very  little  heavy  material  was  encoun- 
tered. Holes  were  drilled  and  blasted  in  small  lots  and  no  ex- 
plosive troubles  of  any  serious  moment  were  encountered. 

During  the  year  1907,  mining  operations  assumed  much  larger 
proportions,  about  one  hundred  four-inch  Star  Well  Drills  and 
one  hundred  and  fifty  Tripod  Drills  being  in  operation.  Drill 
holes  were  spaced  on  centers  varying  from  twelve  to  eighteen 
feet  and  with  depths  of  from  fifteen  to  as  high  as  sixty  feet,  blasting 
charges  ranging  from  two  hundred  to  as  high  as  one  thousand 
pounds  of  dynamite  per  hole,  depending  upon  the  class  of  material 
being  mined.  Five  million  eighty-seven  thousand  pounds  of 
dynamite  were  ordered  and  used  during  this  year.  Serious 
troubles  then  began  to  develop  from  the  encountering  by  steam 
shovels  of  unexploded  dynamite.  A  number  of  shovels  were 
damaged  and  a  number  of  operators  injured.  It  was  im- 
mediately ascertained  that  this  unexploded  dynamite  resulted 
from  detonator  failures  and  not  from  the  quality  of  dynamite 
being  used.  Investigations  were  therefore  started  under  the 
direction  of  Lieutenant-Colonel  D.  D.  Gaillard,  U.  S.  A.,  Corps 
of  Engineers,  and  Division  Engineer  of  the  Central  Division, 
along  the  line  of  determining  the  cause  of  detonator  failures. 
The  heavy  charging  of  holes  and  the  condition  of  work  along  the 
Canal  often  required  detonators  to  be  left  in  charged  holes  for 
twenty-four  hours  or  more  before  blast  was  set  off.  A  number 
of  tests  were  immediately  made  upon  the  imperviousness  of 
detonators  to  the  waters  encountered  in  these  drill  holes.  De- 
tonators were  left  immersed  under  varying  heads  of  waters  taken 
from  drill  holes  for  from  twenty-four  to  thirty-six  hours  and  were 
then  dissected  to  ascertain  to  what  extent  water  had  penetrated 
detonator  shell.  It  was  discovered  that  some  of  the  brands  of 
detonators  then  in  use  became  thoroughly  saturated  and  the  ful- 
minate ruined  after  a  twenty-four  hour  immersion.  While  other 
classes  did  not  absorb  as  much  water,  nearly  all  were  found  to 
have  become  affected.  Three  different  brands  of  detonators 
manufactured  in  the  United  States  and  one  brand  of  detonator 
manufactured  in  Germany  were  tested  under  heads  of  from 
twenty-five  to  forty  feet  of  water  and  none  were  found  impervious 


iv]  Congress  of  Applied  Chemistry  87 

after  immersion  from  twenty-four  to  thirty-six  hours.  This 
discovery  was  most  surprising  in  view  of  the  fact  that  these 
detonators  were  the  best  products  then  obtainable  in  the  com- 
mercial market.  The  only  difference  between  the  requirements 
of  the  work  on  the  Isthmian  Canal  and  that  of  ordinary  mining 
work  was  the  length  of  time  which  detonators  were  left  in  charged 
holes  before  being  fired,  and  it  is  therefore  presumed  that  the 
manufacturers  had  not  heretofore  been  called  upon  to  furnish 
a  detonator  which  would  stand  immersion  under  a  head  of  water 
for  more  than  from  two  to  three  hours.  As  an  example  of  the 
deterioration  of  one  brand  of  detonator  after  immersion,  the 
results  of  a  series  of  tests  are  given  in  accompanying  table,  marked 
Exhibit  "A." 

When  it  was  discovered  that  detonators  were  not  impervious 
to  drill  hole  waters,  it  was  assumed  that  these  waters  contained 
some  free  acid  which  attacked  the  detonator  shells.  This  assump- 
tion seemed  to  have  good  foundation  from  the  fact  that  a  micro- 
scopic examination  of  detonator  shells  after  immersion  showed 
minute  holes  just  below  the  sulphur  plug.  A  number  of  these 
detonators  and  samples  of  the  water  from  drill  holes  was  then  sent 
to  the  Chief  Sanitary  Officer  at  Ancon  for  a  report  as  to  what 
acids,  if  any,  were  causing  the  deterioration  of  detonator  shells. 
Tests  and  examinations  made  in  Ancon  Laboratory  showed  that 
this  shell  deterioration  was  not  due  to  free  acids,  but  was  due 
primarily  to  the  composition  and  construction  of  the  exploder  it- 
self. A  summation  of  the  conclusion  of  these  tests  is  as  follows: 

1.  That  the  different  kinds  of  water  used  for  detonator  im- 
mersion made  little  difference  in  the  net  results  when  the  same 
conditions  of  time  of  immersion  and  pressure  were  maintained. 

2.  That  the  number  of  failures  to  get  a  normal  explosion  of 
cap  increased  almost  geometrically  with  the  length  of  time  of 
immersion  and  the  hydrostatic  pressure  to  which  submitted. 

3.  That  corrosion  began  on  the  internal  portion  of  shell  at  or 
near  the  point  of  contact  between  sulphur  plug  and  the  loosely 
packed  portion  of  the  charge  usually  opposite  or  a  little  above  the 
level  of  the  platinum  bridge. 

A  full  copy  of  the  report  of  Ancon  Laboratory  is   herewith 
attached,  marked  Exhibit  "B." 


88  Original  Communications:  Eighth  International        [VOL. 

Detonator  manufacturers  were  notified  of  the  troubles  encoun- 
tered, and  two  of  these  manufacturers  later  developed  and  fur- 
nished to  the  Commission  detonators  which,  after  test,  proved 
practically  impervious  to  water  under  heads  of  forty  to  sixty 
feet.  In  one  brand  of  these  detonators  a  composition  or  cement 
plug  is  inserted  in  shell  just  above  the  loose  fulminate  and  at 
the  point  !v>  where  shell  deterioration  had  occurred.  Above  this 
composition  plug  a  black  viscous  compound  is  inserted  and  above 
this  compound  the  usual  sulphur  plug  is  put  in  as  a  cap.  If 
this  sulphur  plug  causes  any  deterioration  of  shell  no  leakage 
through  deterioration  at  this  point  can  reach  the  fulminate. 

The  other  detonator  is  composed  of  a  double  jacket  or  shell. 
The  inner  shell  contains  the  usual  packed  fulminate  at  the  bottom, 
a  small  quantity  of  gun  cotton,  the  bridge,  and  the  usual  sulphur 
plug  at  the  top.  This  inner  shell  is  set  into  an  outer  shell,  filled 
with  a  black  compound  resembling  fluid  tar  which  completely 
envelops  the  inner  or  explosive  shell.  If  inner  shell  is  deteriorated 
or  perforated  by  sulphur  action,  the  outer  shell  and  compound  will 
prevent  any  moisture  reaching  fulminate.  The  detailed  con- 
struction of  these  two  classes  of  shells  is  shown  in  attached  sketch, 
marked  Exhibit  "C." 

With  impervious  detonators  it  was  assumed  that  accidents 
from  unexploded  dynamite  would  become  matters  of  history. 
However,  in  the  spring  of  1908  the  number  of  missed  holes  and 
the  consequent  amount  of  unexploded  dynamite  dug  up  by  steam 
shovels  reached  such  proportions  as  to  call  for  a  careful  study 
of  all  conditions  which  might  in  any  way  cause  misfires. 

THE    NON-UNIFORMITY    OF    DETONATOR    CURRENT    EXPLOSIVE 

VALUES 

With  impervious  detonators  in  service,  and  the  knowledge 
that  the  dynamite  being  used  was  of  the  best  grade  obtainable, 
it  was  then  decided  to  investigate  the  power  for  exploding  de- 
tonators. 

While  these  investigations  were  being  carried  on,  the  necessity 
for  reducing  the  number  of  missed  holes  caused  the  issuance  of 
instructions  to  reduce  the  spacing  of  drill  holes  to  thirteen  feet 
as  a  maximum  so  as  to  thus  utilize  more  largely  the  explosion 


iv]  Congress  of  Applied  Chemistry  89 

of  one  hole  to  detonate  surrounding  holes  (in  which  detonator 
had  misfired)  by  either  sympathetic  explosion  or  by  means  of 
the  hot  gases  from  exploded  holes  penetrating  the  fissures  to  ad- 
joining holes.  While  the  issuance  of  the  above  orders  largely 
assisted  in  reducing  the  amounts  of  unexploded  dynamite,  it 
must  be  understood  that  results  obtained  from  explosives  de- 
tonated by  surrounding  holes,  instead  of  by  their  own  detonator, 
are  very  poor,  in  that  the  holes  detonating  first  open  up  fissures 
and  cracks  which  prevent  the  full  force  of  the  second  detonation 
being  obtained.  In  this  connection,  the  attention  of  this  Congress 
is  invited  to  the  fact  that  many  detonator  failures  in  ordinary 
mining  operations  are  never  discovered,  because  adjoining;  holes 
explode  the  charge  of  the  defective  detonator. 

Until  the  spring  of  1908  all  blasts  in  the  Canal  excavation 
were  discharged  by  means  of  hand  batteries  operating  from  ten 
to  as  high  as  seventy  detonators  wired  in  series.  These  batteries 
had  been  furnished  the  Isthmian  Canal  Commission  in  various 
types  and  sizes,  marked  and  guaranteed  as  being  good  to  explode 
from  ten  to  one  hundred  detonators.  The  manufacturers  furnish- 
ing these  batteries  also  furnished  small  rheostats  which  contained 
resistances  marked  for  field  purposes  as  representing  specified 
numbers  of  caps.  For  example:  If  a  battery  was  marked  good 
for  seventy  detonators,  one  of  these  rheostats,  set  at  a  resistance 
equal  to  seventy  detonators  with  thirty  foot  leads,  could  be  placed 
in  circuit  with  the  battery  and  one  detonator.  The  battery  would 
then  be  operated  and  if  detonator  exploded,  battery  was  con- 
sidered to  be  good  for  the  explosion  of  seventy  detonators,  in  that 
it  had  fired  one  detonator  with  current  passing  through  a  resistance 
equal  to  the  other  sixty-nine  or  seventy  detonators.  It  was  the 
practice  to  test  all  of  these  batteries  with  these  rheostats  before 
putting  them  into  service,  and  while  a  few  were  found  defective, 
the  majority  were  found  fully  capable  of  exploding  the  one  de- 
tonator through  the  resistance  of  the  full  number  of  detonators 
for  which  battery  was  marked  good.  A  short  description  of  these 
batteries  (commonly  used  in  all  blasting  operations)  is  herewith 
considered  apropos  for  the  benefit  of  those  not  familiar  with 
their  construction. 

The  common  type  of  these  batteries  is  a  small  series  of  com- 


90  Original  Communications:  Eighth  International        [VOL. 

pound  series  wound  generator,  located  on  a  horizontal  plane  as 
a  base,  in  a  rectangular  wooden  box.  A  vertical  rod  projects 
through  the  top  of  box,  one  side  of  which  rod  has  been  cut  into 
teeth  forming  a  rack.  A  train  of  gears  operating  between  this 
rack  and  generator  revolves  the  armature  of  generator  as  this 
rack  rod  is  pushed  down  into  box.  The  rate  of  armature  revolu- 
tion depends  entirely  upon  the  speed  with  which  the  rack  rod  is 
moved.  The  rack  rod  upon  reaching  the  bottom  of  box  breaks 
one  contact  and  connects  another  which  throws  the  generator 
in  series  with  the  external  circuit  (firing  wires  and  detonators). 
From  this  construction  it  is  readily  understood  that  with  the 
beginning  of  the  push  down  movement  of  rack  rod,  the  generator 
voltage  builds  up  in  the  form  of  a  curve,  reaching  its  maximum 
when  rack  rod  reaches  the  bottom  of  box  and  throws  external 
circuit  into  series  with  generator.  It  is  also  readily  seen  that  the 
power  applied  to  the  generator  by  the  operator  ceases  at  the  instant 
this  rack  rod  reaches  the  bottom  of  box,  and  thus  at  the  same  in- 
stant that  firing  circuit  is  connected,  and  from  that  time  on,  the  gen- 
erator's only  source  of  power  is  that  derived  from  the  momentum 
of  the  revolving  armature.  The  voltage  characteristic  of  blasting 
batteries  is,  therefore,  a  curve,  which  reaches  a  maximum  at  the 
instant  that  blasting  circuit  is  connected  to  generator,  the  peak 
of  which  curve  could  be  nothing  more  than  a  point,  in  that  voltage 
immediately  begins  to  drop  with  the  connection  of  the  blasting 
circuit.  We,  therefore,  obtain  from  one  of  these  blasting  batteries 
only  a  pulsation  of  current  lasting  through  a  fractional  part  of 
a  second.  It  is  important  that  the  brevity  of  this  current  pulsa- 
tion be  thoroughly  appreciated  in  order  to  understand  the  weak- 
ness and  uncertainty  of  blasting  batteries  in  exploding  detonators. 
We  have  on  our  construction  work  no  instruments  delicate  enough 
to  accurately  measure  and  record  the  voltage  curve  of  one  of  these 
batteries,  but  a  study  of  such  a  curve  would  be  extremely  interest- 
ing, and  would,  I  am  sure,  prove  the  conclusions  reached  through 
practical  experiments  and  from  crude  experimental  apparatus. 

After  ascertaining  that  the  field  batteries  were  sufficiently  power- 
ful to  explode  one  detonator  through  a  resistance  equal  to  the  num- 
ber of  detonators  for  which  battery  was  guaranteed,  it  occurred  to 
the  writer  that  our  detonator  troubles  were  probably  due  to  the  series 


iv]  Congress  of  Applied  Chemistry  91 

method  of  connecting  these  detonators  in  circuit.  With  only  an 
instantaneous  pulsation  of  current  the  explosion  of  a  large  number 
of  detonators  must  be  impossible  unless  said  detonators  are  so 
uniform  in  construction  as  to  allow  of  their  bridge  being  heated 
to  the  explosive  point  by  the  same  amount  of  current  with  the 
same  time  element. 

A  study  was  then  determined  upon  and  made  of  the  two  vari- 
ables entering  into  the  heating  limits  of  these  detonator  bridges. 
It  was  quickly  ascertained: 

1.  That  with  the  time   element   of   current   flow   constant, 
detonators   exploded   with   variable   amounts   of   current.     For 
example:  In  testing  twenty-five  detonators,  picked  at  random 
from  stock,  it  was  found  that  with  the  time  element  constant 
the  current    value  for  exploding  these  detonators  varied  from 
forty-four  one-hundredths  to  seventy-six  one-hundredths  of  an 
ampere. 

2.  That   with    current    flow    constant,    detonators   exploded 
under  variable  time  elements.     For  example:  It  was  found  from 
tests  that  with  a  constant  current  value  of  five-tenths  of  an  ampere 
and  with  variable  time  element  detonators  exploded  with  above 
amount  of  current  flow  through  them  in  from  two  one-hundreths 
to  seven  one-hundredths  of  a  second. 

With  this  knowledge  it  was  readily  understood  why  a  large 
number  of  detonators  wired  in  series  could  not  be  counted  upon 
to  explode  from  a  momentary  current  from  a  blasting  battery, 
even  though  that  battery  had  fired  one  detonator  through  a 
resistance  equal  to  the  number  of  detonators  for  which  battery 
was  guaranteed. 

With  fifty  detonators  wired  in  series  and  requiring  an  exploding 
current  value  varying  from  forty-four  one-hundredths  to  seventy- 
six  one-hundredths  of  an  ampere,  that  detonator  requiring  the 
lowest  current  value  to  explode  would  naturally  be  the  first  to 
break  down,  thus  breaking  the  circuit  and  leaving  detonators 
requiring  high  current  value  unexploded. 

The  apparatus  used  in  obtaining  the  above  current  and  time 
values  is  fully  described  in  an  attached  appendix,  marked  Ex- 
hibit "D."  This  apparatus  was  the  best  that  could  be  obtained 
on  the  Isthmus,  and  while  it  may  appear  crude  from  a  scientific 


92  Original  Communications:  Eighth  International        [VOL. 

standpoint,  it  was  considered  and  proved  to  be  accurate  enough 
to  demonstrate  by  comparative  results  the  non-uniformity  of  the 
detonators  tested. 

The  results  also  unquestionably  demonstrated  the  impracti- 
cability of  avoiding  missed  holes  when  using  a  large  number  of 
detonators  wired  in  series,  no  matter  what  or  how  powerful  the 
source  of  current  supply. 

In  order,  however,  to  verify  the  conclusions  that  missed  holes 
were  sure  to  be  encountered  where  detonators  were  wired  in  series, 
a  number  of  tests  were  made  with  one  hundred  detonators  con- 
nected in  series  with  a  fifteen  kilowatt  transformer  with  voltage 
of  110,  220  and  440.  In  no  instance  were  we  able  to  explode  the 
entire  one  hundred  detonators  with  the  first  closing  of  switch, 
although  in  every  instance  it  was  found  that  there  were  no  de- 
fective detonators  in  circuit.  For  example :  In  testing  one  hundred 
detonators  we  would  explode  from  ninety  to  ninety-five  upon 
the  first  closing  of  switch.  Those  which  did  not  explode  would 
be  re-connected  in  circuit  with  transforner  and  would  all  explode 
but  one  or  two  upon  the  second  closing  of  switch.  The  opening 
of  unexploded  detonator  showed  same  to  be  double  bridged. 
We  thus  obtained  conclusive  evidence  that  double-bridged  de- 
tonators or  those  requiring  high  current  values  for  exploding 
could  not  be  counted  upon  to  detonate  when  wired  in  series  with 
detonators  requiring  low  current  values  for  exploding. 

A  number  of  experiments  were  then  made  by  wiring  detonators 
in  parallel  with  source  of  current  from  the  same  transformer. 
In  every  case  where  detonators  were  wired  in  parallel,  all  exploded 
at  the  first  closing  of  switch.  While  without  question  those  de- 
tonators requiring  the  lowest  current  value  exploded  first,  the  time 
element  between  the  explosion  of  detonators  was  inappreciable 
to  either  sight  or  hearing  of  investigator  standing  within  two 
hundred  feet  of  the  detonators,  which  were  laid  upon  the  open 
ground. 

The  results  of  experiments  caused  orders  for  the  immediate 
construction  of  some  eight  miles  of  primary  pole  line  along  the 
banks  of  the  Canal  between  Bas  Obispo  and  Pedro  Miguel,  the 
installation  of  transformers  at  every  thousand  feet  along  this 
pole  line,  and  the  stringing  of  secondary  wire  from  transformers 


iv]  Congress  of  Applied  Chemistry  93 

throughout  the  blasting  districts  in  this  eight  miles  of  territory. 

The  use  of  blasting  batteries  was  immediately  prohibited 
throughout  this  section,  except  for  the  springing  of  holes  and  for 
such  other  light  work  as  would  not  result  in  accidents  in  case 
detonators  failed  to  explode. 

In  all  heavy  mining  operations  detonators  were  connected  in 
parallel  to  feed  wires  of  number  Twelve  B.  and  S.  gauge,  strung  on 
stakes  over  the  holes  to  be  exploded.  These  feed  wires  were  then 
connected  by  blasting  wiremen  to  the  secondaries  of  number 
Two  Brown  and  Sharpe  gauge  wire  which  had  been  strung  from 
transformers  along  the  ground  on  portable  trestles. 

Some  little  time  was  required  to  initiate  and  educate  the  mining 
forces  into  the  practice  of  parallel  wiring  and  firing  of  detonators 
from  power  line.  Some  prejudice  was  encountered  on  the  part 
of  old  miners  who  had  been  accustomed  throughout  years  of 
experience  to  the  use  of  blasting  batteries  and  series  wiring  of 
detonators.  A  number  of  these  miners  insisted  that  they  had 
never  had  any  missed  holes  when  using  blasting  batteries  and 
offered  to  wager  the  writer  that  they  could  fire  with  their  own 
particular  blasting  batteries  any  number  of  detonators  (up  to 
the  battery  capacity)  wired  in  series.  In  order  to  convince  these 
men  of  their  error  in  judgment,  the  writer  allowed  a  number  to 
demonstrate  to  him  personally  the  handling  of  blasting  battery 
with  detonators  wired  in  series.  In  only  one  instance  did  the 
battery  (marked  good  for  fifty  holes)  explode  ten  detonators 
connected  in  series.  The  surprise  and  consternation  of  the 
operators  was  remarkable  and  can  only  be  accounted  for  by  the 
fact  that  throughout  their  mining  experience  they  had  been  using 
blasting  batteries  for  the  explosion  of  detonators  in  holes  close 
enough  together  to  cause  the  explosion  of  one  hole  by  another, 
thus  giving  the  miner  the  impression  that  all  detonators  had  fired. 
The  writer  is  of  the  opinion  that  not  more  than  ninety-five  per 
cent  of  detonators  connected  in  series  have  ever  exploded,  no  matter 
what  source  of  current  had  been  utilized. 

The  installation  of  power  lines  and  the  adoption  of  the  parallel 
wiring  and  firing  of  detonators  produced  such  an  immediate 
reduction  of  missed  holes  and  increased  efficiency  of  explosives 
that  this  method  was  adopted  throughout  practically  the  entire 
Canal  construction. 


94  Original  Communications:  Eighth  International        [VOL. 

The  author  believes,  and  our  experience  seems  to  verify  the 
conclusion,  that  it  is  impracticable  to  manufacture  for  commercial 
purposes  detonators  which  would  be  so  uniform  in  the  required 
current  value  and  time  element  for  explosion  as  to  make  the  use 
of  blasting  batteries  and  series  wiring  (regardless  of  the  magnitude 
of  power  source)  as  safe  and  sure  as  the  parallel  wiring  in  which 
non-uniform  and  double-bridged  detonators  are  sure  to  explode. 

The  tests  made  on  the  Isthmus  and  the  practical  results  obtained 
from  the  parallel  wiring  and  firing  of  detonators  confirm  most 
positively  the  conclusions  that  blasting  batteries  and  series  wiring 
of  detonators  is  an  unsafe  and  questionable  practice. 

It  would  be  extremely  hard  to  estimate  the  amount  of  money 
which  the  Isthmian  Canal  Commission  has  saved  by  the  change  from 
series  to  parallel  wiring  and  firing  of  detonators.  The  unexploded 
holes  due  to  detonators  misfiring  caused  large  losses  by  ground 
being  insufficiently  broken  and  the  consequent  result  of  delays 
incident  to  "dobeying,"  to  say  nothing  of  the  extra  amount  of 
dynamite  used.  In  addition,  a  number  of  steam  shovel  cranemen 
were  hurt  by  digging  into  unexploded  dynamite,  which  resulted 
in  a  timidity  on  the  part  of  steam  shovel  operators,  which  largely 
reduced  their  output. 

The  firing  of  detonators  wired  in  parallel  naturally  requires  a 
large  current  output  and  consequently  a  much  more  expensive 
current  source  than  the  ordinary  hand  battery.  The  magnitude 
of  the  work  in  hand  must  determine  the  advisability  of  making  the 
necessary  installation  for  parallel  wiring  and  firing  of  detonators. 
If  the  work  is  of  sufficient  magnitude  to  warrant  such  an  ex- 
penditure, the  danger  to  operators  is  greatly  reduced,  the  efficiency 
of  the  explosives  is  largely  increased,  and  the  general  results 
obtained  are  much  more  economical  and  satisfactory. 

EXHIBIT    "A" 

Test  No.  1  of  Fifteen  35-foot  Electric  Fuses 
Fuses  immersed  together  in  25-foot  well  drill  hole  having  19 
feet  water  in  hole.  Fuses  remained  in  hole  June  2,  5  P.M.  to  June 
4,  7  A.M.  38  hours  in  water.  Connected  15  and  pumped  battery. 
Trial  No.  1—14  exploded;  1  failed.  Trial  No.  2—1  exploded; 
none  failed. 


iv]  Congress  of  Applied  Chemistry  95 

Test  No.  2  of  Sixteen  16-foot  Electric  Fuses 
Fuses  made  up  into  primers  to  spring  25-foot  holes  having  10 
to  20  feet  of  water  in  each.  Fuses  remained  in  hole  June  3,  3 
P.M.  to  June  4,  8  A.M.  17  hours.  Connected  sixteen  and  pumped 
battery  —  failed.  Tried  singly, —  second  failed ;  fourth  and 
fifth  exploded  together  from  proximity;  tenth,  eleventh  and 
twelfth  exploded  together  from  proximity  and  burned  dynamite 
in  hole  making  smoke;  fourteenth  failed.  Judging  from  appear- 
ances, exploders  did  not  properly  detonate  dynamite  in  many 
instances. 

Test  No.  3  of  Sixteen  20-foot  Electric  Fuses 
Fuses  immersed  as  in  Test  No.  2  and  tried  in  same  manner 
singly   after   all   failed   connected.     Third   failed   completely, — 
when  opened,  found  wet  fulminate  inside. 

Test  No.  4  of  Eighteen  2 4-foot  Electric  Fuses 
Fuses  immersed  as  in  tests  Nos.  2  and  3  and  tried  connected 
and  failed,  then  singly  to  get  results.     Fifth,  sixth  and  seventh, 
eighth  and  ninth  holes  exploded  by  proximity.     One  failed  com- 
pletely. 

Test  No.  6  of  Fifteen  30-foot  Electric  Fuses 
Fuses  immersed  together  in  25-foot  well  drill  holes  having  20 
feet  water  in  hole.  Fuses  remained  in  hole  June  2,  5  P.M.  to  June 
5,  7  A.M.  62  hours  in  water.  Connected  15  and  pumped  battery, — 
failed.  Tried  5, —  exploded;  tried  5, —  failed;  tried  5, —  3  ex- 
ploded. Opened  two,  found  wet  fulminate.  Single  No.  1  exploded ; 
No.  2  exploded  and  burned;  No.  3  like  "nigger  chaser";  No.  4 
failed  completely;  No.  5  burned  like  a  match. 

N.B.    After  as  many  as  15  times  having  battery  pumped, 
fulminate  could  be  made  to  burn  ineffectively. 

Test  No.  5  of  Ten  35-foot  Electric  Fuses 
Fuses  made  into  primers  of  one  stick  dynamite  each  immersed 
in  25-foot  well  drill  holes  having  depth  18  feet  water.  Fuses 
remained  in  hole  June  2,  5  P.M.  to  June  5,  7  A.M.  62  hours.  Con- 
nected 7, —  2  on  surface  of  ground, —  5  in  holes.  Result, —  all 
had  no  good  effect  to  detonate,  the  two  on  surface  having  only 


96  Original  Communications:  Eighth  International        [VOL. 

blown  dynamite  into  pieces.  Connected  three  in  same  hole  and 
pulled  battery  which  exploded  with  poor  effect,  one  on  being 
pulled  out  showed  low  explosive  effect,  blowing  hole  in  side  of 
copper  shell  only. 

EXHIBIT  "B" 
BOAKD  OF  HEALTH  LABORATORY, 

ANCON  HOSPITAL,  May  21,  1908. 
To  the  Superintendent,  Ancon  Hospital. 

Sir: — In  compliance  with  the  request  of  the  Chief  Sanitary 
Officer  I  have  the  honor  to  render  the  following  report:  Chemical 
No.  174. 

Report  on  an  investigation  into  the  cause  of  corrosion  of  copper 
shells  of  electric  exploders  and  failure  to  detonate  the  charge  of  Powder. 

I.  Waters  from   Test  Blast  Holes.    Both   samples   of  water 
submitted  showed  practically  the  same  amount  of  alkalinity  and 
sulphur  trioxide  (S03)  as  follows: 

Alkalinity  204-212. 

Sulphur  Trioxide  0.00943  %  (per  cc.). 

The  alkalinity  is  nearly  twice  as  much  as  that  of  the  highest 
of  the  reservoir  waters  during  the  height  of  the  dry  season, 
namely,  Gorgona,  which  was  114. 

The  sulphur  is  not  present  as  free  sulphuric  acid,  but  in  combina- 
tion with  the  bases  present  which  is  clearly  shown  by  the  high 
amount  of  alkalinity.  From  this  fact  it  may  be  inferred  that 
the  corrosive  action  of  the  sulphuric  acid  is  largely  neutralized 
by  its  presence  in  a  state  of  combination  with  the  bases.  This 
low  direct  corrosive  effect  of  the  water  from  blast  holes  is  also 
clearly  shown  by  comparative  experiments  which  I  have  made 
with  distilled  water  and  Ancon  Tap  water. 

II.  Cause  of  Corrosion  of  Copper  Shells  of  Electric  Exploders. 
The  results  of  a  series  of  experiments  under  a  wide  variety  of 
conditions  prove  fairly  conclusively  that  the  cause  of  the  corrosion 
is  internal  and  due  primarily  to  the  composition  and  construction 
of  the  exploder  itself. 

The  experiments  (briefly  stated)  were  carried  out  as  follows: 
The  several  types  of  exploders  submitted  were  soaked  in  distilled 
water  and  water  from  test  blast  holes  under  a  head  of  about  one 
foot,  some  of  which  were  bared  of  the  paraffine  or  asphaltum  like 


iv]  Congress  of  Applied  Chemistry  97 

covering  where  the  wires  enter  the  copper  shell,  while  the  remainder 
were  left  in  the  normal  condition.  Following  this  series  another 
set  of  the  exploders  with  the  ends  treated  in  the  same  manner 
were  immersed  in  a  section  of  three  inch  gas-pipe  filled  with  Ancon 
Tap  water  at  depths  of  about  twelve  and  twenty  feet,  depending 
on  the  length  of  the  fuse  wires. 

Tests  of  85  fuses  of  the  different  types  (mostly  of  the  older  forms  of 
exploder)  by  the  Magneto  exploding  battery,  showed: 

1.  That  the  different  kinds  of  water  used  made  little  difference 
in  the  net  result  when  the  same  conditions  of  time  of  immersion 
and  pressure  were  maintained. 

2.  That  the  number  of  failures  to  get  a  normal  explosion  of 
the  cap  increased,  I  might  say,  almost  geometrically  with  the 
length  of  time  of  immersion  and  the  hydrostatic  pressure  to  which 
submitted  (particularly  the  latter). 

A  detailed  examination  of  those  exploders  which  failed  to  give 
a  normal  explosion  was  made  and  the  following  results  were 
deduced  and  verified  in  most  cases  by  direct  experiment. 

1.  The  corrosion  occurs  at  or  near  the  point  of  contact  between 
the  sulphur  plug  and  the  loosely  packed  portion  of  the  charge, 
usually  opposite  or  a  little  above  the  level  of  the  platinum  bridge. 

2.  An  examination  of  the  interior  surface  of  the  copper  shell, 
both  above  and  below  the  point  of  corrosion,  shows  that  the  copper 
is  more  or  less  corroded  wherever  the  sulphur  comes  in  contact 
with  it  and  an  amalgam  of  metallic  mercury  occurs  in  the  neighbor- 
hood where  the  break  in  the  shell  occurs,  often  on  the  outside  as 
well  as  the  inside  of  the  shell.     Small  globules  of  mercury  may 
often  be  seen  scattered  all  over  that  portion  of  the  shell  which 
comes  in  contact  with  the  loosely  packed  upper  and  darker  colored 
crystalline-like  portion  of  the  charge,  which  I  take  to  be  the 
fulminate.     Finally  there  seems  to  be  little  or  no  corrosion  in 
the  lower  part  of  the  shell  where  the  lighter  colored  compressed 
powder  form  of  the  charge  is  located.     This  latter  portion  of  the 
charge  occasionally  failed  to  be  detonated,  although  the  upper 
portion  of  the  charge  had  exploded. 

(This  lower  compressed  portion  of  the  charge  is  said  to  be  gun- 
cotton,  and  its  general  appearance  and  character  agree  with  this 
statement.) 


98  Original  Communications:  Eighth  International        [VOL. 

III.     Cause  of  Failure  to  Detonate  the  Charge  of  Powder. 

Taking  into  consideration  all  of  the  foregoing  experimental 
facts  and  data,  I  believe  that  the  prime  cause  of  failure  to  detonate 
the  powder  is  due  to  the  entrance  of  moisture  (principally  when 
subjected  to  pressureomder  water)  into  that  portion  of  the  charge 
in  the  vicinity  of  the  fuse.  In  the  majority  of  cases  this  moisture 
gets  in  directly  through  the  wall  of  the  shell  in  the  immediate 
vicinity  of  the  fuse.  However,  it  may  occasionally  get  in  from 
the  end  where  the  wires  enter,  since  defects  in  the  copper  shell 
and  sulphur  plug  have  been  found  sufficient  to  allow  of  the  entrance 
of  water,  especially  when  under  pressure. 

The  entrance  of  water  into  one  make  of  exploder,  in  which  there 
is  a  considerable  thickness  of  rather  porous  paper  between  the 
sulphur  plug  and  interior  surface  of  the  copper  shell,  probably 
takes  place  by  means  of  this  bibulous  layer  of  paper  from  the 
end  where  the  wires  enter.  The  three  of  this  variety  which 
were  submitted,  all  of  which  had  failed  to  explode  (one  in  a  blast 
hole  and  the  other  two  under  experimental  conditions),  bear  out 
this  statement.  The  copper  shells  also  show  little  corrosion  in 
the  neighborhood  of  the  fuse  and  upper  portion  of  charge  and 
practically  none  above  the  fuse  since  the  sulphur  does  not  come 
into  direct  contact  with  the  copper. 

The  fact  that  the  sulphur  is  put  in  the  shell  in  the  melted  con- 
dition, accounts  for  its  marked  corrosive  action  everywhere  it 
comes  in  direct  contact  with  the  copper,  and  also  the  hot  sulphur 
coming  in  contact  with  the  fulminate  in  the  vicinity  of  the  fuse 
probably  accounts  for  the  setting  free  of  mercury  which,  together 
with  the  nitrogen  compounds  formed  at  the  same  time,  sulphide 
of  copper  previously  formed,  and  also  a  possible  sulphide  of  mer- 
cury, furnish  a  sufficient  supply  of  corrosives  to  further  eat  away 
the  copper  shell. 

Keeping  these  facts  and  conditions  in  mind,  one  can  readily 
see  .how  length  of  time  of  storage,  length  of  time  of  immersion 
and  hydrostatic  pressure  would  effect  the  deterioration  and  failure 
of  the  exploder  to  do  the  work  for  which  it  was  intended. 

I  have  also  discovered  marked  corrosion  of  the  bare  copper 
wires  just  above  the  bridge  and  even  loosening  of  the  platinum 
bridge  which  might  account  for  the  failure  of  same,  but  this  I 
think  is  of  minor  importance. 


iv]  Congress  of  Applied  Chemistry  99 

The  recent  modification  of  another  make  of  exploder  also  shows 
the  same  process  at  work  on  the  interior,  but  modified  by  the 
plug  (also  containing  sulphur)  existing  between  the  sulphur 
fillings  and  charge,  and  the  thick  asphaltum-like  exterior  coating. 

Only  four  of  the  new  form  were  submitted;  one  of  the  first  two, 
bared  of  coating  where  wires  enter  and  soaked  in  one  foot  of  dis- 
tilled water  for  forty-eight  hours,  exploded  only  with  a  very  feeble 
report.  One  of  the  second  two  bared  at  the  end  and  the  other 
not  were  soaked  in  twenty  feet  of  tap  water  for  forty-eight  hours, 
and,  when  taken  out,  the  ends  of  both  were  broken  off  at  the 
usual  place,  and  the  same  conditions  found  to  exist  as  in  the  case 
of  the  older  variety.  It  was  also  noted  that  in  handling  this 
variety  the  wires  at  point  of  entrance  are  very  apt  to  be  loosened 
from  the  asphaltum-like  protection  and  thus  afford  another 
point  for  water  to  gain  entrance  along  the  insulation  of  the  wires, 
and  the  sulphur  filling. 

I  have  also  found  that  if  sulphur  is  simply  melted  in  an  empty 
copper  shell,  upon  cooling  the  shell  is  often  found  to  contain 
very  fine  cracks,  usually  running  lengthwise,  due  presumably  to 
the  sudden  expansion  of  the  sulphur  upon  solidifying. 

Respectfully, 

(Signed)      R.  W.  NAUSS,  M.D., 

Chemist. 
(Signed)      G.  H.  WHIPPLB, 

Acting  Chief  of  Laboratory. 
W.... 

EXHIBIT     "  D  " 

Description  of  Apparatus  employed  in  obtaining  comparative 
values  of  current  and  time  element  required  for  exploding  Detonators. 

While  the  apparatus  described  below  may  appear  crude  and 
unreliable  in  obtaining  accurate  data,  it  must  be  borne  in  mind 
that  the  only  object  of  tests  was  to  ascertain  values,  which,  by 
comparison,  would  show  whether  detonators  required  a  uniform 
current  and  time  element  for  their  explosion. 

Comparing  current  explosive  values  with  time  element  constant. 

For  this  purpose  current  was  taken  from  a  15  K.W.-110  Volt, 
B.C.  Generator,  which  generator  was  kept  operating  at  a  constant 


n 


Congress  of  Applied  Chemistry  103 

speed  and  constant  voltage  on  a  uniform  load.  Current  for  test 
purposes  was  passed  through  a  bank  of  lamps,  then  through 
ammeter  and  rheostat  to  a  double  pole  double  throw  switch. 
With  this  double  pole  switch  in  one  position,  rheostat  was  set 
so  as  to  give  the  desired  amount  of  current,  usually  beginning 
with  30/100  ampere.  A  piece  of  hard  fiber  with  a  copper  insert 
as  shown  in  diagram  was  mounted  upon  a  table.  A  piece  of  spring 
copper  connected  with  coil  spring  was  pivoted  on  this  fiber.  One 
of  the  terminals  of  double  throw  switch  as  shown  in  diagram  was 
connected  to  the  dethc&jitor  to  be  tested.  Other  side  of  detona- 
tor was  connected  ^  the  strip  of  spring  copper.  The  copper 
insert  in  fiber  was  connected  with  the  other  terminal  of  double 
throw  switch. 

After  rheostat  had  been  set  for  30/100  ampere,  the  spring  copper 
or  switch  blade  was  pulled  back  across  copper  insert  and  holding 
plug  inserted.  Double  throw  switch  was  then  placed  in  position 
to  connect  detonator  in  circuit.  Holding  plug  was  then  removed, 
which  allowed  the  blade  of  spring  copper  to  make  a  wiping  contact 
across  the  copper  insert  for  only  such  length  of  time  as  was  required 
for  this  blade  to  pass  over  the  copper  insert.  If  detonator  under 
test  did  not  explode,  double  throw  switch  was  then  placed  in 
such  position  as  to  throw  detonator  out  of  circuit  and  rheostat 
was  adjusted  so  as  to  give  32/100  ampere.  Blade  of  detonator 
switch  was  again  pulled  back  and  held  by  plug.  Double  throw 
switch  was  then  placed  in  position  to  connect  detonator  in  circuit 
and  holding  plug  removed,  allowing  blade  to  again  make  a  wiping 
contact  across  copper  insert.  Each  detonator  was  continued 
under  test  by  the  above  method  with  current  values  being  in- 
creased by  increments  of  2/100  ampere  until  detonator  finally 
exploded.  With  the  same  coil  spring  in  service  and  the  spring  blade 
drawn  back  to  the  point  of  holding  plug  at  each  test,  it  was  assumed 
that  the  time  element  for  current  flow  would  be  nearly  enough 
constant  for  all  practical  and  comparative  purposes.  As  stated 
in  the  body  of  this  paper,  detonator  current  explosive  values 
varied  from  44/100  to  76/100  ampere. 

Comparing  time  element  explosive  values  with  current  constant. 

The  devising  of  some  method  by  which  detonators  could  be 
connected  in  circuit  for  1,  2,  or  3/100  of  a  second,  required  som 


104  Original  Communications:  Eighth  International 

expediency  in  that  we  are  working  on  a  construction  job  with  no 
refined  instruments  or  testing  equipment  on  hand.  A  150  H.P. 
Ball  Engine  operating  a  100  K.W.  3-Phase  60-Cycle  Generator 
was  brought  into  service.  This  engine  was  put  under  constant 
load  and  the  speed  held  at  120  revolutions  per  minute.  Tests  of 
speed  by  tachometer  showed  variation  of  not  more  than  one 
revolution  per  minute.  The  fly-wheel  of  this  engine  was  covered 
with  a  shellacked  canvas,  which  canvas  was  then  cut  out  in  a  form 
as  shown  in  attached  diagram.  A  stand  carrying  a  flat  copper 
brush  was  then  mounted  in  front  of  fly-w^dd  so  that  brush  could 
be  given  a  wiping  contact  on  face  of  fly-wheel  over  any  of  the 
seven  spaces  cut  in  canvas.  With  brush  bearing  on  face  of  fly- 
wheel at  right  side,  the  amount  of  bare  iron  over  which  brush 
would  pass  (four  and  one-half  inches)  represented  a  time  element 
of  1/100  of  a  second.  With  brush  removed  to  second  space  and 
wiping  over  nine  inches  of  the  bare  face  of  fly-wheel,  we  obtained 
a  time  element  of  2/100  of  a  second.  With  brush  bearing  on 
third  space  and  wiping  over  13J  inches  of  bare  face  of  fly-wheel, 
we  obtained  a  time  element  of  3/100  of  a  second.  With  the  seven 
spaces  on  fly-wheel  we  were  able  to  obtain  time  elements  of  1,  2, 
3,  4,  5,  6,  and  7/100  second.  Current  for  testing  detonators  was 
obtained  from  the  same  source  as  in  other  tests,  passing  through 
bank  of  lamps,  ammeter  and  rheostat  to  double  pole  switch. 
The  lower  set  of  terminals  of  this  double  pole  switch  were  con- 
nected through  detonator,  brush  and  engine  shaft.  The  current 
value  was  set  at  5/10  ampere,  and  the  time  element  then  varied 
from  1/100  second  up  until  detonator  exploded  The  brush 
would  be  released  and  allowed  to  press  against  fly-wheel  just 
long  enough  to  insure  having  passed  over  the  bare  face  of  wheel 
two  or  three  times  or  during  two  or  three  revolutions  of  fly-wheel. 
Under  these  tests  detonators  were  found  to  explode  with  5/10 
ampere  and  with  time  elements  varying  from  2  to  14/100  second. 
These  detonators  which  did  not  explode  under  time  elements 
of  7/100  second  were  set  to  one  side  and  later  tested  with  engine 
running  at  60  revolutions,  under  which  conditions  each  space 
on  face  of  fly-wheel  represented  two  instead  of  1/100  second, 
giving  us  a  time  element  up  to  14/100  second. 


IMPROVED   DENSIMETER 

BY  WALTER  O.   SNELLING 
Pittsburgh,   Pa. 

The  specific  gravity  of  gunpowder,  black  blasting  powder,  and 
similar  explosives,  is  usually  expressed  as  " gravimetric  density," 
and  represents  the  apparent  specific  gravity  of  a  selected  volume 
of  explosive,  the  space  between  the  grains  of  powder  not  being 
allowed  for.  In  the  study  of  ballistics,  and  in  comparison  of  the 
work  done  by  varying  grades  of  black  blasting  powder,  even  the 
rather  meager  information  which  is  furnished  by  the  " gravi- 
metric density"  of  a  sample  is  of  considerable  value  in  compari- 
son between  powders,  and  several  types  of  apparatus  have  been 
designed  to  enable  the  gravimetric  density  of  a  powder  to  be 
readily  determined.  The  determination  is  in  any  case  a  simple 
matter,  and  practically  consists  of  nothing  more  than  the  deter- 
mination of  the  weight  of  powder  required  to  fill  even  full  a  se- 
lected vessel  of  known  volume. 

The  true  or  absolute  density  of  black  powder  or  other  similar 
type  of  explosive  has  long  been  recognized  to  be  a  decidedly  more 
important  factor  than  the  apparent  specific  gravity  or  "gravi- 
metric density."  It  is  well  known  that  exact  comparison  be- 
tween two  explosives  can  only  be  made  on  the  basis  of  their  true 
density,  since  two  powders  of  widely  different  density  can  have 
the  same  apparent  specific  gravity  where  the  denser  powder  is 
in  large,  angular  grains  and  the  lighter  powder  is  in  small  and  well- 
rounded  grains.  In  such  a  case  the  small  and  rounded  grains 
pack  so  much  closer  than  the  larger  angular  grains  that  even  a 
considerable  divergence  in  true  density  may  be  entirely  without 
effect  in  producing  a  difference  in  the  apparent  specific  gravity. 

Owing  to  the  solubility  in  water  of  the  nitrates  present,  the 
usual  picnometer  method  of  determining  density  has  to  be  modi- 
fied for  use  with  black  powder  and  similar  explosives,  and  several 
types  of  densimeter  have  been  devised  for  such  use.  Of  these, 
densimeters  using  mercury  to  replace  the  air  filling  the  spaces 

105 


106  Original  Communications:  Eighth  International 

in  and  around  the  grains  of  powder  have  been  found  to  be  the 
most  satisfactory  (densimeter  of  Bianchi,1  Ricq,2  Bode,3  Michel- 
son,4  Hoffmann,5  Marchand6),  but  other  types  of  densimeter  are 
also  well  known  in  which  the  volume  occupied  by  the  powder  is 
measured  by  a  change  in  volume  or  pressure  of  air  or  other  gas 
present  in  a  vessel  with  the  powder,  application  being  made  of 
Boyle's  law  to  estimate  the  portion  of  the  known  volume  of  the 
reservoir  which  is  filled  with  powder  (Holecek  volumeter,7  Say 
stereometer,8  Kopp  volumeter8).  The  density  of  powder  is  also 
sometimes  determined  in  the  ordinary  picnometer  bottle,  making 
use  of  absolute  alcohol  in  place  of  water.  Absolute  alcohol  is  not 
without  effect  upon  the  constituents  of  gunpowder,  and  the  re- 
sults obtained  by  this  method  are  not  as  accurate  as  those  reached 
in  an  apparatus  using  mercury.  The  method  has,  however,  the 
advantage  of  not  requiring  any  special  apparatus. 

In  the  study  of  black  powder  and  black  blasting  powder  by  the 
Bureau  of  Mines,  it  was  found  desirable  to  distinguish  powders 
on  the  basis  of  their  true  or  absolute  density,  and  a  comparison 
of  the  many  types  of  apparatus  which  have  been  devised  for  this 
purpose  indicated  the  possibility  of  arranging  apparatus  of  simpler 
construction,  which  would  equally  well  fulfill  the  purpose  of 
determining  real  or  absolute  density  of  black  powder.  The  im- 
proved densimeter,  devised  by  the  writer,  is  to  be  considered  as 
only  a  variant  of  the  many  devices  which  have  been  previously 
used  in  the  determination  of  absolute  density. 

In  the  new  densimeter,  advantage  is  taken  of  the  production 
of  a  Torricellian  vacuum  within  the  apparatus  itself,  thus  entirely 
eliminating  the  use  of  a  separate  air  pump,  and  the  device  as 


xKast,  Anleitung  zur  Chem.  und  Phys.  Untersuchung  der  Spreng-und 
Zund-stoffe,  page  1001. 

2Guttmann,  The  manufacture  of  explosives,  page  306. 

8Guttmann,  The  manufacture  of  explosives,  page  304. 

4Ann.  Kept.  Secy.  U.  S.  Navy,  1879,  page  70. 

6Guttmann,  The  manufacture  of  explosives,  page  299. 

"Guttmann,  The  manufacture  of  explosives,  page  297. 

7Kast,  Anleitung  zur  Chem.  und  Phys.  Untersuchung  der  Spreng-und  Zund- 
stoffe,  page  1002. 

8Guttmann,  The  manufacture  of  explosives,  page  299. 


'M- 


110  Original  Communications:  Eighth  International        [VOL. 

constructed  has  been  found  to  fully  answer  the  many  require- 
ments which  have  been  met  with  in  the  practical  examination 
of  blasting  powder,  and  has  proved  to  be  an  apparatus  possessing 
not  only  a  high  degree  of  accuracy,  but  also  of  extremely  simple 
operation. 

In  Figure  1  a  vertical  section  of  the  apparatus  is  shown,  (a) 
representing  the  vessel  within  which  the  Torricellian  vacuum  is 
produced,  (b)  the  cover  of  this  vessel,  (c)  a  valve  placed  in  the 
top  of  the  cover,  to  allow  exit  of  air  entrapped  within  the  reservoir. 
The  flange  around  the  reservoir  (a),  as  well  as  the  flange  upon 
the  cover  (6),  is  to  provide  a  mercury  seal  covering  such  parts 
of  the  apparatus  as  are  open  to  the  outside  air.  (d)  is  an  iron 
pipe,  which  must  be  about  1  meter  in  length,  leading  from  the 
vessel  (a)  to  the  mercury  reservoir  (e).  The  reservoir  (e)  is  of 
iron,  completely  closed  except  for  the  two  pipes  (d)  and  (/).  The 
pipe  (f)  is  connected  to  a  source  of  water  under  pressure  at  valve 
(w),  and  an  outlet  pipe  at  valve  (x).  (i)  is  a  framework  designed 
to  hold  the  picnometer  bottle  or  other  suitable  vessel  (h). 

To  determine  the  absolute  density  of  a  sample  of  powder,  the 
picnometer  bottle  (h)  is  partly  or  wholly  filled  with  the  material 
whose  density  is  to  be  determined,  and  is  then  placed  firmly  in 
the  clamp  or  framework  (i).  The  framework  and  picnometer  bottle 
are  not  placed  in  the  reservoir  (a),  taking  the  position  shown  in 
the  drawing.  The  frame  and  bottle  are  lighter  than  mercury, 
but  are  held  in  proper  position  in  the  mercury  in  the  reservoir 
by  means  of  the  small  projection  shown,  set  in  the  wall  of  the 
vessel  (a).  The  cover  (6)  is  placed  upon  the  reservoir,  and  is 
screwed  down.  The  valve  (x)  being  first  opened  quite  wide,  valve 
(w)  is  opened  until  there  is  a  steady  flow  of  water  from  the  supply 
pipe  through  the  outlet  pipe  (x).  Valve  (x)  is  now  closed,  and 
as  the  outlet  pipe  is  thus  cut  off,  the  water  is  forced  into  the  res- 
ervoir (e)  and  raises  the  mercury  through  the  pipe  (d).  The 
valve  (c)  being  open,  mercury  is  allowed  to  flow  in  until  the  res- 
ervoir (a)  is  completely  full,  and  until  the  mercury  has  also  over- 
flowed so  as  to  fill  the  mercury  seals  around  the  cover  (6)  and 
around  the  valve  (c).  When  this  condition  has  been  reached  valve 
(z)  is  opened,  and  valve  (c)  is  closed,  and  as  the  pipe  (d)  is  of 
greater  vertical  height  than  760  mm.,  the  mercury  in  the 


IV] 


Congress  of  Applied  Chemistry 


111 


FIGURE  4 


upper  part  of  the  reservoir  (a)  flows  out  through  the  pipe  (d) 
and  a  partial  vacuum  is  produced  in  the  upper  portion  of  the  res- 
ervoir (a).  The  air  surrounding  the  grains  of  powder  in  the  pic- 
nometer  (h)  rises  into  the  evacuated  space,  and  at  the  end  of  a 
few  minutes  has  been  largely  entrapped  in  the  conical  space  in 
the  cover  (b) .  The  valve  (x)  is  now  closed,  the  valve  (c)  is  opened, 
and  because  of  the  pressure  within  the  apparatus  being  greater 
than  the  atmospheric  pressure,  owing  to  the  pressure  of  the  water, 
the  bubbles  of  air  entrapped  rise  through  the  mercury  seal  to 


112  Original  Communications:  Eighth  International        [VOL. 

the  upper  part  of  the  cover  (6) .  Valve  (c)  is  closed  as  soon  as  the 
air  has  been  completely  driven  out,  and  valve  (x)  is  opened,  and 
this  operation  is  repeated  until  no  further  bubbles  of  air  rise 
through  the  mercury  seal  when  the  valve  (x)  is  closed  and  the 
valve  (c)  is  opened. 

When  this  condition  has  been  reached  it  will  be  found  that  all 
the  air  in  the  picnometer  bottle  (h)  has  been  replaced  by  mercury, 
and  upon  now  taking  off  the  cover  of  the  apparatus,  removing 
the  picnometer  bottle  (h)  from  the  framework  and  weighing  it, 
a  weight  is  obtained  which  represents: 

Wt.  of  bottle  (h)  +  wt.  of  powder  taken  +  wt.  of  mercury  filling 
all  portions  of  the  bottle  not  filled  with  powder. 

Since  the  weight  of  the  empty  bottle,  and  the  weight  of  the  bottle 
completely  filled  with  mercury,  form  the  known  constants  of 
the  apparatus,  being  determined  with  accuracy  when  the  appara- 
tus is  first  used,  and  as  the  specific  gravity  of  mercury  is  also 
known,  it  is  evident  that  there  is  now  available  all  the  information 
required  to  calculate  the  density  of  the  powder  under  examination. 
In  order  that  the  method  of  calculation  may  be  fully  understood, 
an  illustrative  example  is  here  given: 

Weight  of  picnometer  18.4  grams 

Weight  of  picnometer  full  of  mercury  1375.8  grams 
Weight  of  mercury  required  to  completely  fill  the 

picnometer  1357.4  grams 
Weight  of  picnometer  plus  sample  of  powder  taken  97.6  grams 
Weight  of  picnometer  18.4  grams 
Weight  of  sample  of  powder  taken  79.2  grams 
Weight  of  picnometer  plus  powder  plus  mercury  re- 
placing air  spaces  886.1  grams 
Weight  of  picnometer  plus  powder  97.6  grams 
Weight  of  mercury  replacing  all  spaces  in  picnometer  788.5  grams 

The  mercury  displaced  by  powder  equals  1357.4  grams  minus 
788.5  grams,  or  568.9  grams  mercury  which  would  be  required 


iv]  Congress  of  Applied  Chemistry  113 

to  occupy  the  same  volume  as  the  powder  contained  within  the 
picnometer.  This  amount,  568.9  grams,  divided  by  13.55,  the 
specific  gravity  of  mercury,  gives  41.98  as  the  volume  in  cc.  of  the 
sample  of  powder  taken.  Since  the  weight  of  this  amount  of  pow- 
der is  79.2  grams,  the  density  of  the  powder  must  be  79.2  divided 
by  41.98,  or  1.886,  absolute  density.  It  is  of  course  evident  that 
when  determinations  are  made  at  other  than  standard  conditions 
of  temperature  correction  for  the  decreased  density  of  mercury 
due  to  expansion  must  be  made,  by  applying  the  customary 
formula. 

The  powder  in  this  particular  experiment  was  of  the  granu- 
lation known  as  FFF.  From  this  example  it  will  be  understood 
that  the  operation  of  determining  the  absolute  density  of  powder 
by  the  densimeter  consists  essentially  in  determining  the  weight 
of  mercury  required  to  completely  fill  a  picnometer  bottle,  and 
then  determining  the  amount  of  mercury  which  corresponds  to 
the  volume  occupied  by  the  sample  of  powder  taken.  From  this 
data,  with  the  known  specific  gravity  of  mercury,  the  absolute 
density  of  the  powder  is  at  once  obtained. 

The  gravimetric  density  of  the  powder  in  the  above  sample, 
as  determined  by  weighing  a  given  volume  of  the  powder,  poured 
into  a  vessel  of  the  standard  size  and  shape,  was  1.176.  The 
absolute  density,  1.866,  is  thus  seen  to  differ  greatly  from  the 
ordinary  or  gravimetric  density.  The  per  cent  of  open  spaces 
between  the  grains  of  powder  in  this  particular  sample  is  found 
from  the  above  data  to  be  35.16  per  cent  of  the  entire  volume 
taken  up  by  the  powder. 

The  following  results,  representing  the  study  of  29  samples 
of  black  blasting  powder,  collected  from  one  of  the  coal-mining 
fields  in  which  black  blasting  powder  is  still  largely  used,  give 
a  good  idea  of  the  usefulness  of  a  comparison  of  the  apparent  and 
true  density  of  black  powder.  These  29  samples  were  all  differ- 
ent, and  represented  the  product  of  a  number  of  manufacturers. 
The  table  shows  the  gravimetric  density  and  the  absolute  density 
of  each  of  the  samples,  and  the  per  cent  of  voids. 


114          Original 

Communications  : 

Eighth  International 

[VOL. 

Improved  densimeter 

Sample 

Absolute 

Gravimetric 

Per  cent  of 

number 

density 

density 

voids 

1 

1.791 

1.15 

35.79 

2 

1.775 

1.18 

33.52 

3 

1.859 

1.17 

37.06 

4 

1.779 

1.13 

36.48 

5 

1.749 

1.13 

35.39 

6 

1.764 

1.15 

34.81 

7 

1.783 

1.18 

33.82 

8 

1.764 

1.19 

32.54 

9 

1.744 

1.17 

32.91 

10 

1.859 

1.17 

37.06 

11 

1.775 

1.17 

34.08 

12 

1.789 

1.16 

35.16 

13 

1.857 

1.20 

35.38 

14 

1.766 

1.18 

33.18 

15 

1.744 

1.14 

34.63 

16 

1.830 

1.15 

37.16 

17 

1.865 

1.20 

35.66 

18 

1.759 

1.18 

32.92 

19 

1.761 

1.17 

33.56 

20 

1.783 

1.17 

34.38 

21 

1.739 

1.16 

33.29 

22 

1.731 

1.09 

37.03 

23 

1.879 

1.18 

37.20 

24 

1.851 

1.15 

37.87 

25 

1.772 

1.16 

34.54 

26 

1.775 

1.15 

35.21 

27 

1.745 

1.16 

33.52 

28 

1.798 

1.19 

33.82 

29 

1.855 

1.18 

36.39 

This  table  shows  clearly  how  unreliable  the  gravimetric  den- 
sity of  an  explosive  is,  as  a  measure  of  its  true  density.  Explo- 
sive No.  3,  one  of  the  explosives  whose  true  density  was  very  high 
(1.859),  shows  exactly  the  same  gravimetric  density  (1.17)  as 
does  sample  9,  whose  true  density  is  one  of  the  lowest  of  the 


rv]  Congress  of  Applied  Chemistry  115 

29  examined.  A  still  more  marked  variation  is  that  shown 
between  samples  21  and  23.  Although  the  gravimetric  density 
of  these  two  samples  differs  by  but  .02,  the  absolute  density 
of  the  two  samples  is  represented  by  the  difference  between 
1.879  in  the  case  of  sample  23  and  1.739  in  the  case  of 
sample  21. 

The  importance  of  determinations  .of  absolute  density  has 
long  been  recognized  in  connection  with  the  study  of  military 
powders,  and  the  usefulness  of  determinations  of  absolute  density 
of  black  powder  for  mining  purposes  is  now  receiving  greater 
recognition  than  it  has  at  any  previous  time.  Being  unaffected 
by  the  size  of  the  grains  of  powder  or  their  angularity,  absolute 
density  presents  at  once  a  measure  of  the  physical  uniformity 
of  black  blasting  powders  in  regard  to  specific  gravity. 

Since  dynamite  is  usually  packed  hard,  it  is  commonly  believed 
that  the  true  density  and  the  apparent  density  of  the  cartridge 
differ  but  little,  and  that  the  well  packed  stick  of  dynamite  pre- 
sents few,  if  any,  interstices  or  spaces  filled  with  air.  To  test 
this  point  a  sample  of  40  per  cent  dynamite  was  taken,  and  its 
absolute  density  was  determined  upon  the  densimeter.  The 
apparent  specific  gravity  of  this  explosive  had  been  found  by 
careful  measurement  to  be  1.24;  showing  that  even  in  this  well 
packed  sample  of  dynamite  there  was  present  25.53  per  cent 
open  or  pore  space.  A  number  of  other  samples  of  the  dynamite 
class  were  similarly  examined,  and  the  per  cent  of  pore  space 
was  found  to  vary  in  different  samples  from  18.62  per  cent  to  a 
maximum  of  over  30  per  cent. 

In  conclusion,  it  may  be  stated  that  the  densimeter  of  the  con- 
struction herein  described  has  for  more  than  a  year  been  in  prac- 
tical use  in  the  laboratory  of  the  Bureau  of  Mines,  and  in  the 
course  of  that  time  has  been  used  in  a  wide  range  of  work.  In 
this  time  it  has  given  perfect  satisfaction,  and  has  proved  to  be 
an  instrument  of  decided  accuracy.  Check  and  duplicate  de- 
terminations agree  to  the  third  decimal  place  —  a  degree  of  accu- 
racy which  is  seldom  attained  in  work  of  this  sort,  but  which  be- 
comes possible  in  this  instrument  because  of  the  fact  that  all 
weights  made  represent  the  mercury  occupying  the  volume  of 
the  powder,  and  accordingly  errors  hi  weighing  produce  very 


116  Original  Communications:  Eighth  International 

small  differences  in  the  absolute  density,  owing  to  the  high  spe- 
cific gravity  of  the  mercury  upon  which  the  weights  are  based. 
In  the  determination  of  the  density  of  black  blasting  powder 
this  instrument  furnishes  a  means  of  conveniently,  quickly  and 
accurately  determining  the  absolute  density  of  a  sample  of  powder, 
and  thus  enables  comparisons  to  be  readily  made.  In  construc- 
tion and  operation  this  instrument  seems  to  be  simpler  than 
any  of  the  types  of  apparatus  now  commercially  available  for 
the  purpose  of  determining  the  absolute  density  of  black  powder. 


THE  EFFECT  OF  THE  NITROTOLUENES  ON  THE  DE- 
TERMINATION  OF  NITROGLYCERIN   BY 
MEANS   OF  THE  NITROMETER 

BT  C.   G.  STORM 
Bureau  of  Mines,   Pittsburgh,   Pa. 

Among  the  coal  mining  explosives  submitted  to  the  Bureau 
of  Mines  for  tests,  a  considerable  percentage  contain  nitroglycer- 
in  together  with  nitrotoluenes,  the  principal  object  of  the  latter 
ingredient  being  to  reduce  the  freezing  point  of  the  mixture. 
The  nitrotoluenes  employed  for  this  purpose  are  generally  the 
commercial  liquid  di-  or  tri-nitrotoluenes,  which  are  mixtures  of 
the  various  nitrosubstitu  tion  products  of  toluene.  Frequently 
the  more  or  less  pure  crystalline  di-or  tri-nitro  compounds  are 
used,  and  less  often  liquid  ortho-nitro toluene. 

In  the  analysis  of  such  explosives,  the  nitroglycerin  together 
with  the  nitrotoluene  is  obtained  in  the  ether  extract,  the  ether 
removed  by  evaporation  in  a  small  weighed  beaker  and  the  ex- 
tracted material  weighed.  The  evaporation  is  allowed  to  proceed 
spontaneously  at  room  temperature,  usually  over  night,  and  the 
beaker  is  then  placed  in  a  vacuum  desiccator  over  sulphuric  acid 
until  no  odor  of  ether  remains  and  any  moisture  condensed  by 
the  evaporation  of  the  ether  has  been  removed.  The  amount  of 
the  extracted  material  may  be  determined  by  a  direct  weighing 
of  the  beaker  and  contents  after  desiccating  over  night,  or  the 
desiccation  may  be  continued  only  long  enough  to  remove  the 
ether  and  all  but  traces  of  moisture,  for  which  about  3  or  4  hours 
is  usually  sufficient,  and  the  weight  of  extracted  material  found 
from  the  loss  of  weight  on  extraction,  allowance  being  made  for 
the  moisture  originally  present  in  the  explosive. 

The  desiccated  mixture  of  nitroglycerin  and  nitrosubstitution 
product  is  next  transferred  to  the  decomposition  bulb  of  a  nitro- 
meter by  dissolving  from  the  beaker  with  sulphuric  acid  (sp. 
gr.  1.84)  and  nitrogen  determined  in  the  usual  manner.1  If 

Bulletin  No.    Bureau  of  Mines,  " Analysis  of  Explosives." 

117 


118          Original  Communications:  Eighth  International        [VOL. 

crystalline  nitro  compounds  insoluble  in  sulphuric  acid  are  present, 
the  entire  mass  is  washed  into  the  nitrometer  with  the  acid. 
By  the  reaction  with  mercury  and  sulphuric  acid  in  the  nitro- 
meter, nitrates  or  nitrites,  both  inorganic  or  organic,  are  decom- 
posed, liberating  all  of  their  nitrogen  as  nitric  oxide  (NO).  From 
the  volume  of  NO  obtained  the  per  cent  of  such  nitrogen  is  de- 
termined and  from  this  the  nitrate  content  of  the  sample.  Nitro- 
substitution  compounds  are,  however,  not  decomposed  by  the 
action  of  sulphuric  acid  and  mercury,  and  hence  yield  no  nitric 
oxide  in  the  nitrometer. 

It  would  therefore  appear  that  the  amount  of  nitroglycerin 
present  in  a  mixture  with  a  nitrosubstitution  compound  could  be 
accurately  ascertained  by  a  determination  of  the  ester  nitrogen 
by  means  of  the  nitrometer,  and  this  method  has  up  to  the  present 
time  been  the  one  most  commonly  used  for  the  analysis  of  such 
mixtures.  Mono-  and  di-nitrotoluenes  are,  however,  capable  of 
combining  with  more  nitric  acid,  and  it  seemed  reasonable  to 
believe  that  such  compounds  might,  in  the  presence  of  sulphuric 
acid,  react  with  a  portion  of  the  nitric  acid  liberated  from  the 
nitroglycerin  by  the  sulphuric  acid,  and  thereby  become  more 
highly  nitrated.  Such  reaction  would  naturally  diminish  the 
volume  of  nitric  oxide  liberated,  and  the  amount  of  nitroglycerin 
calculated  from  this  gas  volume  would  be  correspondingly  low. 

A  series  of  experiments  were  made  to  determine  the  effects 
of  known  amounts  of  the  various  nitrotoluenes  on  the  determina- 
tion of  nitroglycerin  in  the  nitrometer.  Various  mixtures  of 
each  of  the  nitrotoluenes  with  nitroglycerin  of  known  purity  were 
weighed  in  a  small  beaker,  about  10  cc.  of  sulphuric  acid  (95- 
96%)  added  quickly,  the  mixture  stirred  and  transferred  to  the 
generating  bulb  of  the  nitrometer,  the  beaker  and  nitrometer 
cup  being  completely  washed  with  several  portions  of  acid,  a 
total  of  about  25  cc.  of  the  sulphuric  acid  being  used.  The  gen- 
erator was  then  shaken  in  the  usual  manner  until  the  decompo- 
sition was  complete,  the  NO  transferred  to  the  reading  tube, 
and  its  volume  noted.  By  dividing  the  reading  of  the  gas  vol  ume 
found  by  the  theoretical  volume  representing  1  gram  of  nitro- 
glycerin (18.50%),  the  weight  of  nitroglycerin  found  was  deter- 
mined. Substr acting  this  weight  from  the  weight  of  pure  nitro- 


IT] 


Congress  of  Applied  Chemistry 


119 


glycerin  used  gives  the  error  of  the  determination  due  to  the  pres- 
ence of  the  nitrosubstitution  compound. 

The  results  of  the  determinations  are  given  in  the  following  table. 
All  of  the  nitrotoluenes  used  were  commercial  products  manu- 
factured by  Leitch  &  Co.,  Huddersfield,  Eng.,  a  grade  commonly 
used  by  powder  manufacturers  in  this  country. 

TABLE  I 

DETERMINATION    OF    NITROGLYCERIN    IN    THE    PRESENCE    OP 
NITROTOLUENES 


Test. 


II  III  IV  V  VI 

Nitro-  Nitro- 

Nitro-        Nitro-    Nitrometer  glycerin  glycerin 
glycerin      toluene     •  reading        found          lost 

(grams)1     (grams)     (per  cent)     (grams)  (grams) 

NITROGLYCERIN    AND    ORTHONITROTOLUENE 


VII 

Nitroglycerin 

lost  per  gram 

of  nitrotoluene 

used 


1. 

.9904 

.7236 

10.88   .5881   .4023      .5560 

2. 

.8510 

.4912 

10.70   .5784   .2726      .5549 

3. 

.9016 

.2766 

13.86   .7492   .1524      .5510 

4. 

.8059 

.2526 

12.32   .6660   .1399      .5539 

5. 

1.1083 

.7618 

12.71   .6870   .4213      .5530 

6. 

1.3081 

1.0273 

13.74   .7481   .5600      .5452 

7. 

.8515 

.3084 

12.60   .6811   .1704      .5525 

8. 

.5101 

1.0005 

(No  evolution  of  gas  obtained.) 

9. 

.5530 

1.0000 

(A  very  small  bubble  of  gas  gen- 

erated, volume  too  small  to  read.) 

NITROGLYCERIN    AND    PARANITROTOLUENE 

10.  1.1057       .7505       12.78       .6908       .4149  .5515 

11.  1.0050       .5000       13.50       .7297       .2753  .5506 


NITROGLYCERIN    AND    LIQUID    DINITROTOLUENE 


12. 
13. 
14. 
15. 
16. 


.8134 

1.1000 

13.70 

.7405 

.0729 

.8954 

2.4364 

13.63 

.7367 

.1587 

.7408 

.4982 

13.17 

.7119 

.0289 

.8500 

2.0102 

13.35 

.7216 

.1284 

.7569 

.5104 

13.43 

.7259 

.0310 

.0663 
.0651 
.0580 
.0639 
.0607 


1  The  weights  in  column  I  represent  pure  nitroglycerin  in  the  samples  taken, 
calculated  from  its  purity  (99.91%)  as  determined  by  the  nitrometer. 


120  Original  Communications:  Eighth  International        [VOL. 

NITROGLYCERIN     AND     LIQUID     TRINITROTOLUENE 

17.  .7004  .9469  12.97  .7011  .0007     (gain) 

18.  .7118  2.5245  13.13  .7097  .0008 

19.  .7187  1.0236  13.28  .7179  .0008 

20.  .7049  2.0186  13.00  .7027  .0011 

NITROGLYCERIN    AND    DINITROTOLUENE,     (M.  P.     66-68°) 

21.  .7362       .6963       13.61       .7357       .0005 

22.  .7364       .7347        13.63        .7366        .0002     (gain)- 

NITROGLYCERIN    AND    TRINITROTOLUENE,     (M.  P.     80-81°) 

23.  .7300       .7023       13.51       .7303       .0003     (gain)- 

24.  .7285        .7516        13.47        .7285        .0000 

It  will  be  noted  from  the  above  table  that  neither  pure  di- 
nitrotoluene  nor  trinitrotoluene  have  any  effect  on  the  determi- 
nation of  nitroglycerin.  The  liquid  trinitrotoluene  has  only  a 
slight  influence.  On  the  other  hand,  the  mononitrotoluenes 
(both  ortho  and  para)  and  liquid  dinitrotoluene  each  take  up 
a  definite  amount  of  the  nitric  acid  resulting  from  the  decompo- 
sition of  the  nitroglycerin,  causing  an  error  in  the  determination 
depending  on  the  amount  of  such  nitro  compound  present.  Tak- 
ing an  average  of  the  values  in  column  VII  for  tests  1-7  inclusive, 
it  is  noted  that  one  gram  of  mononitrotoluene  (ortho)  causes 
a  loss  of  .5530  grams  of  nitroglycerin,  equal  to  .1023  grams  of 
nitrogen.  Since,  theoretically,  .1022  gram  of  nitrogen  would  be 
taken  up  in  the  conversion  of  one  gram  of  mononitrotoluene  to 
dinitrotoluene  (C7H7N02  =  10.22%N),  the  results  appear  to 
indicate  that  the  mononitrotoluene  is  completely  converted  to 
dinitrotoluene.  In  test  8  the  nitric  acid  evolved  from  the  nitro- 
glycerin was  entirely  taken  up  by  the  large  excess  of  nitrotoluene 
present,  so  that  no  generation  of  gas  resulted.  In  test  9  the  mix- 
ture was  so  proportioned  that  an  approximate  condition  of 
equilibrium  existed,  that  is,  the  amount  of  nitroglycerin  was  just 
about  sufficient  to  provide  for  the  conversion  of  the  mono- 
nitrotoluene to  dinitrotoluene,  and  leave  no  nitric  oxide  to  be  set 
free.  The  small  bubble  of  gas  obtained  may  readily  be  accounted 
for  by  a  slight  error  in  weighing,  since  a  volume  of  0.10  cc.  NO 
would  be  obtained  from  .0003  gram  cf  nitroglycerin  in  excess 
of  the  theoretical  amount  necessary  for  equilibrium. 


iv]  Congress  of  Applied  Chemistry  121 

Tests  10  and  11  show  an  average  loss  of  .5510  gram  nitrogly- 
cerin,  equivalent  to  .1019  gram  of  nitrogen,  per  gram  of  para- 
nitrotolueme,  or  practically  the  same  figure  as  in  the  case  of  or- 
thonitrotoluene. 

Liquid  dinitrotoluene  (tests  12-16  inc.)  causes  only  a  rela- 
tively slight  loss,  and  as  it  is  evident  from  tests  21-22  that  dinitro- 
toluene itself  has  no  effect,  it  would  seem  reasonable  to  assume 
that  the  loss  is  due  to  the  presence  of  mononitrotoluene  in  the 
liquid  dinitro  compound.  The  average  loss  of  nitroglycerin  in 
tests  12-16  (.0628  gram  for  each  gram  of  liquid  dinitrotoluene) 
is  equivalent  to  the  loss  which  would  be  found  if  each  gram  of 


the  latter  contained  -      —  =  .1136  gram,  or  11.36%,  mononitro- 
.5530 

toluene.  In  order  to  prove  the  presence  of  the  mono  compound 
in  the  liquid  dinitrotoluene,  50  cc.  of  the  latter  were  distilled 
with  steam,  the  distillate  shaken  with  ether,  the  ether  solution 
separated  and  evaporated  by  warming  gently.  A  yellow  liquid 
residue  was  obtained  which  had  a  strong  odor  of  orthonitrotol- 
uene.  On  adding  a  weighed  portion  of  this  residue  to  a  weighed 
amount  of  nitroglycerin  and  determining  the  latter  in  the  nitro- 
meter, a  definite  loss  of  nitroglycerin  was  noted,  as  shown  below. 

Nitro-      Nitro-         Nitroglycerin 

Nitro-        Nitro-  Nitrometer  glycerin  glycerin         lost  per  gram 
glycerin      toluene     reading       found          lost  of  nitrotoluene 

Test.       (grams)     (grams)    (per  cent)  (grams)     (grams)  (grams) 

25.  1.0045      .8004      11.90      .6432      .3613  .4514 

26.  1.0162      .8350      11.84      .6400      .3762  .4505 

Since  one  gram  of  pure  mononitrotoluene  caused  a  loss  of  .5530 
gram  nitroglycerin  (Table  I),  the  above  loss  of  .4510  gram  would 
indicate  that  the  material  distilled  from  the  liquid  dinitrotoluene 

contained    81.55%    mononitrotoluene     I-     -  =  81.55%). 

V      .5530  J 

No  attempt  was  made  to  determine  the  total  content  of  mononi- 
trotoluene in  the  liquid  dinitrotoluene,  owing  to  the  fact  that 
distillation  with  steam  affords  only  slow  and  approximate  separa- 
tion, small  amounts  of  both  di-  and  tri-compounds  passing  over 
in  the  distillate.  Addition  of  acetone  and  potassium  hydroxide 
gave  the  characteristic  red  coloration  produced  by  trinitrotoluene. 
This  color  completely  masks  the  blue  and  yellow  colors  characteris- 


122  Original  Communications:  Eighth  International        [VOL. 


tic  of  the  di-  and  mono-compounds  respectively.  However,  the 
experiment  appears  to  confirm  the  presence  of  mononitrotoluene 
in  the  liquid  dinitrotoluene,  and  verifies  the  conclusions  drawn 
from  the  results  in  Table  I. 

By  a  similar  procedure  a  small  amount  of  a  yellow  distillate 
was  separated  from  liquid  trinitrotoluene.  A  determination  of 
a  weighed  amount  of  nitroglycerin  mixed  with  this  distillate 
showed  a  loss  of  only  .0464  gram  of  nitroglycerin  per  gram  of 
the  distillate,  indicating  about  8.4%  mononitrotoluene  in  the 
latter.  As  the  amount  of  distillate  (.68  gram)  was  only  about 
1%  of  the  weight  of  liquid  trinitrotoluene  used,  it  can  be  seen  that 
the  latter  contains  only  about  .08%  mononitrotoluene,  which 
amount  would  have  a  negligible  effect  on  the  determination  of 
nitroglycerin  in  a  mixture  containing  nitroglycerin  and  iquid 
trinitrotoluene.  (See  tests  17-20,  Table  I.) 

The  following  additional  experiments  were  made  to  show  that 
the  effect  of  mononitrotoluene  on  the  determination  of  nitro- 
glycerin is  not  influenced  by  the  presence  of  the  higher  nitrotol- 
uenes.  Mixtures  were  prepared  similar  to  those  in  Table  I, 
in  which  orthonitrotoluene  and  a  higher  nitro  compound  were 
both  added  to  nitroglycerin.  Determinations  of  the  latter  in- 
gredient in  the  nitrometer  gave  the  following  results: 

TABLE  II 

DETERMINATION    OF    NITROGLYCERIN    IN    THE     PRESENCE     OF    MIX- 
TURES   OF    NITROTOLUENES 


Nitro- 

Nitro- 

Nitroglycerin 

Nitro- 

Nitro- 

Nitrometer 

glycerin 

gtycerin 

lost  per  gram 

of 

Test. 

glycerin 

toluenes 

reading 

found 

lost 

mononitrotoluene 

(grams) 

(grams) 

(per  cent) 

(grams) 

(grams) 

(grams) 

27. 

1.3118 

1.0273a 

13.74 

.7481 

.5637 

.5487 

.4985b 

28. 

.8523 

.3084a 

12.60 

.6811 

.1712 

.5551 

1.7654b 

29.   .9071   .2638a  14.05   .7595   .1476 


30.     1.1772 


1.0173b 
.8073a     13.50 
1.0048d 


.7297       .4475 


.5595 


.5543 


Note:  In  Table  II,  a = orthonitrotoluene,  6= dinitrotoluene  (m.  p.  66-68°), 
C=liquid  trinitrotoluene,  d= trinitrotoluene  (m.  p.  80-81°), 


iv]  Congress  of  Applied  Chemistry  123 

These  values  for  the  loss  of  nitroglycerin  per  gram  of  mono- 
nitrotoluene agree  closely  with  those  found  in  Table  I. 

It  now  remained  to  prove  that  in  the  tests  described,  there  is 
a  complete  conversion  of  mononitrotoluene  to  dinitrotoluene 
when  the  amount  of  nitroglycerin  present  is  sufficient  to  furnish 
the  necessary  quantity  of  nitric  acid. 

The  clear  acid  solution  from  the  nitrometer  in  test  9  (Table  I) 
was  drawn  off  as  completely  as  possible  and  poured  into  about 
250  cc.  of  water,  with  stirring.  After  cooling,  the  emulsion  was 
shaken  with  ether  in  a  separatory  funnel,  the  lower  acid  layer 
drawn  off  and  the  clear  ether  solution  evaporated  in  a  weighed 
beaker.  The  residue  obtained  was  a  light-yellow  crystalline  mass 
weighing  1.2650  grams.  The  1  gram  of  orthonitrotoluene  used 
would  theoretically  be  equivalent  to  1.3284  grams  dinitrotoluene. 
A  second  trial  gave  1.2520  grams  of  the  crystalline  substance. 
This  material  gave  the  characteristic  color  test  for  dinitrotolu- 
ene,— a  blue  coloration  on  adding  potassium  hydroxide  to  an  ace- 
tone solution  of  the  crystals,  showing  that  not  even  small  amounts 
of  trinitrotoluene  were  produced  as  the  red  color  from  the  latter 
would  have  masked  the  blue  color  produced  by  the  dinitrotoluene. 

The  fact  that  mixtures  of  the  mononitrotoluenes  with  nitro- 
glycerin became  warm  on  the  addition  of  sulphuric  acid,  while 
the  separate  ingredients  did  not,  indicated  that  the  nitration  of 
the  mononitrotoluene  occurred  immediately  on  adding  the  acid 
to  the  mixture,  and  before  transferring  it  to  the  nitrometer. 
Experiments  were  therefore  made  with  both  ortho  and  para 
nitrotoluenes,  one  gram  of  each  in  separate  beakers,  being  dissolved 
in  10  cc.  sulphuric  acid,  and  .5530  gram  nitroglycerin  dissolved 
in  10  cc.  sulphuric  acid  added  to  each.  The  mixtures  were  allowed 
to  cool,  poured  into  water,  shaken  with  ether  and  the  ether  ex- 
tract evaporated.  The  1  gram  orthonitrotoluene  yielded  1.3143 
grams,  the  1  gram  paranitrotoluene  1.2996  grams  of  crystalline 
product  (theory  1.3284  grams  dinitrotoluene).  The  two  sub- 
stances obtained  were  different  in  appearance,  that  from  the 
para  compound  crystallizing  readily  from  the  ether  in  large  needles 
while  that  from  the  ortho  compound  became  a  solid  maaauafter 
all  the  ether  had  volatilized.  The  former,  recrystallizedjfrom 
absolute  alcohol  showed  a  melting  point  of  70°,  corresponding 


124  Original  Communications:  Eighth  International        [VOL. 

with  2.4  dinitrotoluene  (m.  p.  70.5°),  while  the  latter  recryst  alii  zed 
from  absolute  alcohol  in  the  form  of  fine  needles,  had  a  melting 
point  of  about  50°,  corresponding  to  2.5.  dinitrotoluene  (m.  p. 
48°). 

In  a  further  experiment,  one  gram  of  orthonitrotoluene  dissolved 
in  10  cc.  sulphuric  acid  was  treated  with  a  mixture  of  10  cc.  of 
sulphuric  acid  and  .657  gram  of  70%  nitric  acid  (equivalent  to 
.5530  gram  nitroglycerin).  From  this  mixture  1.25  grams  di- 
nitrotoluene with  a  melting  point  of  50°  was  separated  by  the 
method  described  above. 

The  fact  that  the  yield  of  dinitrotoluene  was  a  trifle  low  is 
in  a  large  measure  due  to  inaccuracies  of  the  method  of  separation 
and  to  the  volatility  of  the  nitro  compounds  with  ether. 

CONCLUSIONS 

In  the  determination  of  nitroglycerin  in  the  presence  of  one 
or  more  of  the  nitrosubstitution  products  of  toluene  by  means  of 
the  nitrometer,  no  errors  are  introduced  by  the  action  of  pure 
di-  or  tri-nitrotoluenes.  The  mononitrotoluenes,  both  ortho  and 
para,  are,  however,  quantitatively  converted  to  dinitrotoluene 
by  the  nitrating  action  of  the  nitric  acid  liberated  from  the  nitro- 
glycerin by  the  sulphuric  acid.  The  large  excess  of  the  latter  takes 
up  the  water  liberated  by  the  reaction  and  therefore  permits  the 
reaction  to  proceed  until  either  all  of  the  nitric  acid  has  been  used 
or  all  of  the  mononitrotoluene  nitrated  to  the  dinitro-compound. 
Thus,  if  in  a  mixture  of  nitroglycerin  and  mononitrotoluene,  the 
nitroglycerin  present  comprises  not  more  than  35.6%  of  the  total, 
no  nitric  oxide  will  be  generated  in  the  nitrometer.  If  the  pro- 
portion of  nitroglycerin  is  greater  than  this  amount  the  error  of 
the  determination  will  be  equal  to  .55  gram  of  nitroglycerin  for 
every  gram  of  mononitrotoluene  present.  Orthonitrotoluene  was 
found  to  be  converted  to  the  2.5.  dinitrotoluene,  while  the  para- 
nitrotoluene  produced  the  2.4.  dinitrotoluene.  These  relations 
are  not  influenced  by  the  presence  of  the  higher  nitrotoluenes, 
since  trinitrotoluene  cannot  be  produced  from  either  the  mono- 
or  di-compounds  except  by  the  aid  of  higher  temperatures  and 
greater  concentration  of  acids. 

It  is  therefore  apparent  that  in  the  analysis  of  unknown  mixtures 
of  nitroglycerin  with  nitrotoluenes,  the  results  obtained  with 


rv]  Congress  of  Applied  Chemistry  125 

the  nitrometer  are  of  no  value  if  mononitrotoluene  is  present  in 
appreciable  amounts.  The  liquid  mixtures  of  somewhat  indefinite 
composition,  known  as  liquid  di-  or  tri-nitrotoluenes,  affect  the 
determination  according  to  the  amount  of  mononitrotoluene 
present.  In  the  case  of  the  liquid  dinitrotoluene  used  in  the  above 
experiments,  the  results  indicated  a  content  of  11.36  per  cent  of 
mononitrotoluene,  1  gram  of  the  liquid  dinitrotoluene  causing  an 
error  of  .0628  gram  of  nitroglycerin.  In  an  explosive  containing 
25%  nitroglycerin  and  10%  liquid  dinitrotoluene,  the  error  in  the 
determination  of  the  nitroglycerin  by  the  nitrometer  would  then 
be  .628%,  i.e.,  the  per  cent  of  nitroglycerin  found  would  be  24.37 
instead  of  25.00.  Most  of  the  usual  types  of  low  freezing  dynamites 
containing  the  liquid  di-  or  tri-nitrotoluenes  can  therefore  be 
determined  by  means  of  the  nitrometer  without  serious  error. 
The  writer  desires  to  acknowledge  the  valuable  assistance  of 
Mr.  J.  H.  Hunter  and  Mr.  A.  L.  Hyde,  both  of  the  Explosives 
Chemical  Laboratory,  Bureau  of  Mines,  in  the  analytical  work 
of  this  paper. 


RECHERCHES  DE  LA  STATION  D'ESSAIS    DE  LIEVIN 
SUR  LES  EXPLOSIFS  DE  SURETE  POUR  MINES 
GRISOUTEUSES  ET  POUSSIEREUSES 

PAR  MM.  J.  TAFPANEL,  ET  H.  DAUTRICHE 
Station  d'essais  de  Lievin,  France 

I.  Un  explosif  de  surete  ideal  serait  celui  qui,  en  aucune  cir- 
constance,  ne  pourrait  allumer  le  grisou  ou  les  poussi£res  de 
houille.  Un  tel  explosif  n'existe  pas,  et  il  ne  peut  s'agir  que  de 
securite  relative.  La  difficult^  est  de  fixer  les  regies  suivant 
lesquelles  les  explosifs  seront  compare's,  afin  d'eliminer  les  moins 
stirs  et  de  reserver  pour  les  mines  grisouteuses  et  poussiereuses 
ceux  pour  lesquels  la  probability  d'innammation  est  le  plus  re*duite. 

En  France,  jusqu'il  y  a  quelques  mois,  la  regie  etait  de  n'ad- 
mettre  dans  ces  mines  que  des  explosifs  detonants,  a  1'exclusion 
de  la  poudre  noire,  et  avec  la  double  condition  que  leur  temperature 
theorique  de  detonation  soit  infe*rieure  a  1500  ou  1900  degres 
centigrades,  suivant  le  genre  des  travaux,  et  qu'il  ne  se  trouve 
aucun  gaz  combustible  parmi  les  produits  de  la  detonation.  Par 
cette  regie  on  reduisait  trois  des  plus  importantes  causes  d'in- 
nammation: dure*e  de  la  flamme,  temperature  de  la  flamme, 
risque  de  flamme  secondaire  apres  melange  avec  Fair  de  la  galerie. 

En  d'autres  pays,  la  r£gle  est  de  classer  Is  explosifs  d'apr&s 
les  resultats  bruts  d'essais  pratiques  d'inflammation,  executes 
dans  des  conditions  invariables,  en  tirant  Pexplosif  dans  un  canon 
d'acier,  le  plus  sou  vent  sans  bourrage.  Par  cette  regie,  on  admet 
implicitement  que  les  conditions  de  tir  realisees  dans  1'essai 
presentent  assez  d'analogie  avec  celles  de  la  pratique  pour  que  le 
classement  resultant  du  tir  artificiel  soit  applicable  aux  diverses 
variantes  du  tir  reel. 

Aucune  de  ces  regies  ne  donne  complete  satisfaction.  L'an- 
cienne  regie  fran9aise  ne  tenait  pas  compte  de  tous  les  facteurs 
du  probleme  en  sorte  qu'il  pouvait  exister  des  explosifs  relative- 
ment  bons  parmi  ceux  qu'elle  excluait.  Quant  au  classement 
par  les  charges  limites  obtenues  dans  les  essais  pratiques,  il  est 

127 


128  Original  Communications:  Eighth  International        [VOL. 

variable  suivant  les  conditions  des  essais,  et  comme  ces  condi- 
tions different  toujours  quelque  peu  de  celles  de  la  pratique,  il 
y  a  incertitude  sur  la  valeur  pratique  du  classement  obtenu; 
d'autre  part  les  conditions  les  plus  favorables  a  Pinflammation  ne 
sont  pas  ne*cessairement  les  memes  pour  les  divers  types  d'ex- 
plosifs,  en  sorte  qu'en  adoptant  une  formule  invariable  d'essais, 
on  peut  avantager  certains  types  au  detriment  des  autres. 

Pour  aboutir  a  de  meilleures  regies,  il  est  necessaire  d'e*tudier 
de  plus  pres  le  mode  de  fanctionnement  des  explosifs  dans  les 
diverses  circonstances  de  P  experience  et  de  la  pratique,  de  recher- 
cher  quels  sont  les  divers  mecanismes  d'inflammation  du  grisou 
ou  des  poussieres  et  d'approprier  les  me'triodes  d'essai  a  la  nature 
de  Pexplosif  essaye*,  selon  le  mode  d'inflammation  envisage. 

Cette  ample  etude  a  ete*  entreprise  par  la  Station  d'essais  de 
Lie*vin;  elle  est  loin  d'etre  terminee;  nous  pouvons  cependant 
indiquer  des  maintenant  quelques  uns  des  resultats  obtenus. 

II.  Trois  principes  importants  ont  6te*  etablis  ou  confirmes 
par  les  travaux  de  la  Station  d'essais  de  Lievin. 

Le  premier  principe  est  le  suivant: 

La  decomposition  complete,  selon  la  formule  theorique,  est  presque 
toujours  realisee,  dans  la  combustion  en  vase  clos,  lorsque  la  densite 
de  chargement  n'est  pas  trop  faible;  elle  paraU  devoir  etre  egalement 
realisee  dans  les  conditions  de  la  pratique,  en  trous  de  mine  bien 
bourres;  mais,  pour  la  plupart  des  explosifs,  la  decomposition  est 
ires  incomplete  dans  le  tir  au  canon  d'acier,  tel  qu'on  le  pratique 
dans  les  essais,  meme  avec  les  densites  de  chargement  qui  donnent 
la  decomposition  complete  en  vase  clos;  elle  est  encore  plus  incomplete 
dans  le  tir  a  I'air  libre. 

Cette  proposition  a  ete*  etablie  par  des  mesures  calorimetriques 
et  des  analyses  de  gaz. 

Des  combustions  en  vase  clos  ont  ete  realisees  dans  la  bombe 
de  Sarrau  et  Vieille,  placee  dans  un  calorimetre;  les  quantites 
de  chaleur  degagees  (grandes  calories  par  kilogramme  d'explosif), 
mesurees  apres  condensation  de  la  vapeur  d'eau,  sont  portees  au 
tableau  suivant,  en  regard  des  quantity's  theoriques  calcule*es 
dans  Phypothese  d'une  decomposition  complete1. 

^Compositions  centesimales  des  explosifs. 


IV] 


Congress  of  Applied  Chemistry 


129 


Designation 
de  1'explosif 

Chaleur 
theorique 
(eau 
condensee) 

Chaleur  mesuree  pour  lea 
densit6s  de  chargement  ci-dessous 

0,05 

0,1 

0,2 

0,3 

0,4 

Kohlencarbonit           .        ... 

594 

767 

776 
957 
941 

895 
1205 

861 

030 

ssi 

861 

642 

783 

816 
951 
978 

888 
1222 

939 

722 

Grisou-dynamite  couche  .... 
Grisou-naphtalite  couche  sal- 
pe'tre'e    

Sabulite 

Grisou-dynamite  roche 

Grisou-dynamite    roche    sal- 
pe"tr4e                    

Dynamite  n°l  

a 

a 

a 

Designation 
de 
1'explosif 

trate  d'ammoniu 
N'O'H* 

1 

•Sfc 
| 

trate  de  baryum 
N?O«Ba 

1 

ton  azotique 

C21H»2O»8N8 

|g 

J3O 

|2> 

"3 

initronaphtaline 
CioH5Q8N» 

1 

a 

j 

lorure  d'ammoni 
NH<C1 

iciure  de  calcium 
Si*Ca 

.2 

rbonate  de  soude 
CO'Na* 

fc 

g 

£ 

% 

6 

1 

B 

E 

S 

6 

3 

i 

0$ 

O 

Grisou-dyna- 

mite couche. 

87,5 

12 

0,5 

Grisou-dyna- 

mite roche.  . 

70 

29 

1 

Grisou-dyna- 

mite-roche 

salpetree  

65 

5 

29 

1 

Grisou-naphta- 

lite couche 

salpetree  .... 

90 

5 

5 

Grisou-naphta- 

lite roche  sal- 

petree   

86,5 

5 

8,5 

Kohlencarbonit 

34 

1 

25 

39,5 

0,5 

Sabulite  

54 

22 

6 

13 

5 

Dynamite  n°l.. 

75 

25 

Dynamite 

gomme  

92 

8 

Si  Ton  tient  compte  des  erreurs  exp6rimentales  et  de  certaines 
reactions  secondaires,  on  remarquera  qu'il  y  a  bonne  concordance 
entre  les  chaleurs  theoriques  et  les  chaleurs  mesurees,  et  que,  par 
suite,  la  decomposition  peut  etre  conside"ree  comme  complete. 

Pour  mesurer  la  chaleur  degagee  dans  les  conditions  des  essais 
au  canon,  on  a  place  le  canon  a  Tint^rieur  d'un  recipient  clos  de 
9  me.  de  capacite*  (ancienne  chaudiere).  Le  nombre  de  calories 
degage"es  par  la  detonation  des  cartouches  tirees  dans  le  canon, 


130          Original  Communications:  Eighth  International        [VOL. 


est  mesure*  par  Felevation  de  pression  imme*diatement  re*alise"e 
dans  le  recipient,  avant  refroidissement;  un  enregistreur  depres- 
sion special,  construit  pour  l'e*tude  des  explosions  de  poussi£res, 
donne  cette  mesure. 

Des  mesures  analogues  ont  e*te*  faites  pour  le  tir  de  cartouches 
suspendues,  hors  du  canon,  en  se  servant,  pour  plus  de  com- 
modite",  d'un  recipient  de  1  me.  Les  mesures  sont  faites  avant 
condensation  de  la  vapeur  d'eau.  Les  chiffres  porte*s  au  tableau 
suivant  repre*sentent  des  moyennes  de  plusieurs  experiences. 


Designation 
de  1'explosif 

Chaleur 
theorique 
(vapeur  d'eau 
non 
condensee) 

Chaleur  mesuree 

Tir  dans 
le  canon 

Tir  en  cartouches 
suspendues 

Grisou-dynamite  couche. 
Grisou-naphtalite  couche 
salpe"tr6e 

516 

528 
534 

K',' 

684 
716 

747 
752 

1116 
1561 

375 

440 
375 

Ier6chantillon: 
440 
2®  e"chantillon: 
600 

600 
charge  forte 
(8  cartouches) 
340 
charge  faible 
(4  cartouches) 
540 

f  amorcage  10fif)  1 
1  ordinaire:  ll 

150 

250 
330 

190 
280 

325 
295 

900 
|  amorgage 
!  ordinaire:     845 
1  amorgage 
[renforce':      1300 

Kohlencarbonit 

Grisou-dynamite   roche 
salpe'tre'e 

Grisou-dynamite  roche  .  .  . 

Grisou-naphtalite      roche 
salp£tre"e          

Sabulite     

Dynamite  n°l 

Dynamite  gomme   

En  moyenne,  la  chaleur  de"gagee  est,  pour  les  explosifs  de  surete*, 
infe"rieure  de  30%  a  la  chaleur  the"orique  dans  le  cas  des  essais 
au  canon,  et  de  60%  dans  le  cas  du  tir  a  Tair  libre.  La  decomposi- 
tion est  done  tres  incomplete  et  tres  diffe*rente  de  ce  qu'elle  est 
en  vase  clos.  Au  contraire  la  dynamite  n°l  d^tone  a  peu  pres 
compl^tement  a  Tair  libre. 

Une  autre  demonstration  de  l'inach£vement  de  la  de*composi- 
tion  dans  le  tir  au  canon  nous  a  e*te*  donne*e  par  les  analyses  des 


IV] 


Congress  of  Applied  Chemistry 


131 


produits  gazeux  de  la  detonation;  les  parois  d'un  canon  de  tir 
sont  perches  d'un  trou  perpendiculaire  a  1'axe,  prolonge  a  1'ex- 
terieur  par  un  tube  me*tallique  par  lequel  une  partie  des  gaz  est 
refouiee  par  la  pression  au  moment  de  la  detonation,  parvient  a 
un  recipient  renverse  sur  une  cuve  a  eau.  On  a  rapproche,  dans 
le  tableau  ci-dessous,  les  compositions  observees,  des  composi- 
tions theoriques  calcule*es  dans  I'hypothese  d'une  decomposition 
complete. 


Composition 

NI 

Designation 
de  1'explosif 

des  produits 
gazeux  de  la 

02 

CO* 

CO 

H* 

ou  gaz 
doses 

detonation 

comme  N* 

Grisou-dynamite  couche.  .  . 

the*orique 
observed 

29,5 
2,3 

8,5 
15,7 

0,0 
0,2 

0,0 

0,7 

62,0 
81,1 

Grisou-naphtalite  couche  .  . 

the"orique 
observee 

23,7 
4,8 

10,3 
15,6 

0,0 
1,1 

0,0 
0,3 

66,0 

78,2 

Grisou-dynamite  roche  .... 

theorique 
observee 

23,8 
5,3 

21,0 
21,6 

0,0 
1,1 

0,0 
0,0 

55,2 
72,0 

Grisou-naphtalite  roche.  .  .  . 

theorique 
observed 

11,4 
4,6 

21,9 
17,9 

0,0 
1,0 

0,0 
0,6 

66,7 
75,9 

Ce  tableau  montre  que  la  detonation  se  fait  suivant  une  loi 
tout  a  fait  diffe"rente  de  celle  qui  correspond  a  la  decomposition 
complete;  la  proportion  d'oxygdne  libre  est  fortement  reduite; 
on  trouve  un  peu  d'oxyde  de  carbone  et  parfois  d'hydrogene, 
qui  ne  devraient  pas  exister;  dans  les  gaz  doses  comme  azote  on  a 
reconnu  la  presence  de  protoxyde  d'azote;  sur  les  parois  metal- 
liques  et  dans  1'eau  de  la  cuve  on  a  recueilli  des  nitrites  et  nitrates. 
On  remarquera  que  la  densite  de  cbargement,  voisine  de  0,3, 
etait  plutot  superieure  a  celles  qui,  en  vase  clos,  donnent  la  de- 
composition complete. 

Le  deuxieme  principe  general  est  le  suivant: 

Les  corps  qui  se  trouvent,  au  moment  de  la  detonation,  au  contact 
des  produits  de  la  detonation,  peuvent  intervenir  d'une  maniere 
appreciable  dans  les  reactions  explosives  et  modifier  les  probabilites 
d' inflammation  du  grisou  ou  des  poussieres. 


132  Original  Communications:  Eighth  International        [VOL. 

La  demonstration  de  cette  proposition  a  e"te  faite  a  1' occasion 
de  deux  Etudes,  dont  il  sera  question  plus  loin,  relatives  a  1'in- 
fluence  des  enveloppes  et  au  role  des  cordeaux  de*tonants  parfois 
employes  pour  PamorQage  des  explosifs. 

Le  troisieme  principe  est  le  suivant: 

Le  mecanisme  de  I'inflammation  du  grisou  et  des  poussiere  est 
variable  suivant  les  circonstances  du  tir. 

On  connait  ou  entrevoit  plusieurs  de  ces  me*canismes;  on  en 
distinguera  sans  doute  d'autres  dans  Tavenir. 

Le  mode  d'inflammation  du  grisou  differe,  a  bien  des  points 
de  vue,  de  celui  des  poussieres:  c'est  pourquoi  les  classements 
d'explosifs  d'apres  les  essais  au  canon,  obtenus  soit  a  LieVin  soit 
dans  d'autres  sieges  d'expe"riences,  different  suivant  que  le  tir  a 
lieu  en  presence  du  grisou,  ou  des  poussieres  ou  d'un  melange  de 
grisou  et  poussi&res. 

Dans  chacun  de  ces  cas,  d'autres  distinctions  diovent  etre 
faites.  Certains  explosifs,  tire's  dans  certaines  conditions  de  tir, 
de*gagent  des  gaz  combustibles  qui,  apres  melange  avec  P  atmos- 
phere ambiante,  donnent  une  flamme  d'une  dure"e  relativement 
longue;  deux  me*canismes  d'inflammation  sont  alors  possibles, 
suivant  que  le  grisou  ou  les  poussi£res  sont  allumes  par  cette  flamme 
secondaire,  ou  directement  par  les  gaz  brulants  de  la  detonation. 

Ce  dernier  cas  est  le  plus  habituellement  envisage";  Fanalyse 
des  effets  d'e*chauffement  par  compression,  ou  melange  ou  con- 
ductibilite*  et  rayonnement  permettrait  d'y  distinguer  encore 
plusieurs  variantes. 

La  deflagration  fusante  constitue  un  autre  mecanisme,  fort 
different:  par  interposition  de  fragments  de  charbon  ou  pour 
toute  autre  cause,  il  se  produit  un  rate  de  transmission  de  la 
detonation;  mais  le  restant  de  la  charge,  au  lieu  de  de*toner,  brule 
lentement  et  peut  enflammer  le  grisou. 

III.  La  combinaison  de  ces  trois  principes  complique  sin- 
gulierement  la  question:  dans  la  detonation  au  canon  ou  en  car- 
touches suspendues,  les  equilibres  finaux  ne  sont  pas  atteints, 
en  sorte  que  les  moindres  causes  secondaires  influent  sur  la  com- 
position interme*diaire  a  laquelle  aboutissent  des  reactions  qui 
n'ont  pas  eu  le  tempe  de  s'achever;  les  corps  en  contact  avec  les 


iv]  Congress  of  Applied  Chemistry  133 

produits  de  la  detonation  sont,  outre  la  matiere  de  Fenveloppe, 
le  rocher  ou  le  charbon  dans  le  trou  de  mine,  Facier  dans  le  canon 
d'essai,  et  le  role  de  ces  corps  diff e*rents  ne  saurait  etre  identique; 
le  me"canisme  d'inflammation  varie  suivant  les  conditions  du  tir, 
soit  au  fond  de  la  mine,  soit  dans  les  essais,  et  les  diverses  in- 
fluences secondaires  se  font  sentir  differemment  suivant  que  Fin- 
flammation  a  lieu  par  Tun  ou  1'autre  de  ces  me*canismes.  C'est 
pourquoi  la  probability  d'inflammation  varie  considerablement, 
non  seulement  suivant  la  nature  de  Fexplosif  et  Fimportance  de 
la  charge,  mais  encore  suivant  les  conditions  du  tir;  ainsi,  au 
canon  d'acier,  sans  bourrage,  nous  avons  pu  obtenir  des  charges 
limites  variant  de  150  environ  a  plus  de  1000  grammes  pour  les 
grisou-naphtalites  et  grisou-dynamites  couche,  de  50  environ  a 
plus  de  600  gr.  pour  les  grisou-naphtalite  et  grisou-dynamite 
roche. 

Quels  sont  la  nature  et  le  role  des  diverses  causes  de  variation? 
Quelle  est  leur  importance  dans  les  conditions  des  essais?  Peut- 
on  prevoir  comment  elles  interviennent  dans  les  diverses  cir- 
constances  qui  peuvent  se  presenter  dans  le  tir  re"el  au  fond  de 
la  mine?  Tels  sont  les  problemes  qu'il  faut  chercher  a  re"soudre 
et  que  nous  avons  aborde"s  dans  diverses  series  d'essais  dont  nous 
dirons  quelques  mots. 

IV.  Influences  tenant  &  la  composition  chimique  ou  physique  de 
Vexplosif. 

1°  Action  des  sels  alcalins. 

De  petites  quantite"s  de  certains  corps,  introduites  dans  un 
explosif,  peuvent  faire  varier  notablement  les  probabilities  d'in- 
flammation; un  exemple  frappant  en  est  donne  par  Faction  des 
sels  alcalins. 

Les  sels  de  potasse  ou  de  soude,  en  nuages,  s'opposent  a  la  com- 
bustion des  gaz  combustibles,  soit  qu'il  s'agisse  de  1'inflammation, 
dans  Fair  ambiant,  des  produits  degage"s  par  les  explosifs  a  com- 
bustion incomplete,  soit  qu'il  s'agisse  de  Finflammation  d'un 
melange  grisouteux  par  un  explosif;  les  motifs  de  cette  action 
particuliere  ne  sont  pas  encore  nettement  premise's;  on  peut  sup- 
poser  que  ces  sels  ont  pour  effet,  par  leur  volatilisation,  de  main- 
tenir  plus  bas  le  maximum  de  temperature,  sans  toutefois  diminuer 
notablement  la  puissance  de  Fexplosif,  parce  que  les  chaleurs  de 


134  Original  Communications:  Eighth  International        [VOL. 


volatilisation  et  de  dissociation  sont  restitutes  aux  gaz  de  la  de*tona- 
tion  a  une  temperature  assez  eleve*e  pour  intervenir  utilement  dans 
le  travail  de  J'explosif;  on  peut  aussi  penser  que  les  sels  alcalins 
modifient  les  vitesses  de  reaction  comme  fait  la  vapeur  d'eau 
pour  certains  melanges  gazeux  inflammables,  mais  en  diminuant 
ces  vitesses  au  lieu  de  les  augmenter;  cette  sorte  d'action  cataly- 
tique  agirait  a  1'inverse  du  sens  habituel;  il  est  vrai  que  cette 
action  pourrait  etre  indirecte,  dans  Phypothese  ou  les  sels  alcalins 
de*shydrateraient  le  melange  gazeux  et  supprimeraient  ainsi 
Faction  acceleratrice  de  la  vapeur  d'eau. 

Si  Pexplication  the*orique  de  cette  influence  demeure  incertaine, 
le  fait  experimental  a  e*te*  nettement  e*tabli. 


Designation 
de  1'explosif 

Chaleur 
degag6e  pour 
100  gr. 

Chaleur  calculee 
pour  100  gr. 

Coton-poudre  de*canitrique 

(C24H30O40N10) 

seul                       

calories 
184 

detonation  simple  :  96  cal. 

aO,5p,100deC03NaH... 
alp  100    -d°-. 

146 

88 

environ, 
detonation    avec    combustion 
totale    des    produits    dans 
1'oxygene  de  1'air:  242  cal. 
environ. 

a  2  p  100    -d°- 

89 

a  2  p  100  de  NO3K. 

88 

a  3  p  100  de  SO4K2.    .      .  . 

79 

a  2  p.100  de  CO3Ca  
a  4  p  100  de  CO3Mg  

152 
152 

a  10  p  100  de  -d°-   

140 

a  3  p  100  de  N2O6Pb  

140 

Trinitrotoluene  (C7H5O6N3) 
seul     

250 

detonation  simple:  66  cal. 

a  2  p  100  de  NO3K 

117 

environ, 
detonation    avec    combustion 

a  3  p  100    -d°-  

96 

totale:  354  cal.  environ. 

a  4  p  100    -d°-  

82 

a  5  p  100    -d°-  

66 

a  10  p.100  -d°-  

66 

a  6  p.100  de  N206Ba  
alOp.100  d°  

187 
175 

On  fait  detoner  dans  la  chaudiere  calorime*trique  un  explosif 
aboutissant  a  la  decomposition  complete  dans  les  conditions  de 
1'essai  et  donnant  des  gaz  combustibles  susceptibles  de  s'enflammer 


rv]  Congress  of  Applied  Chemistry  135 

apres  melange  avec  1'air  ambiant;  on  mesure  les  calories  de"gage*es; 
elles  sont  superieures  au  chiffre  the"orique,  calcule*  d'apres  1'equa- 
tion  de  decomposition;  la"  difference  correspond  a  la  chaleur 
de*gagee  par  la  combustion  secondaire. 

Si  1'on  recommence  1'essai  en  ajoutant  a  1'explosif  une  petite 
quantite*  de  sel  alcalin,  on  retrouve  la  quantite*  de  chaleur  the*orique, 
ce  qui  prouve  que  la  combustion  secondaire  n'a  pas  eu  lieu;  le 
tableau  suivant  donne  les  re*sultats  obtenus,  et  montre  qu'ils 
sont  inde*pendants  de  la  nature  du  sel  (carbonate,  nitrate  ou 
sulfate),  pourvu  que  la  base  soit  alcaline. 

On  aboutit  aux  monies  conclusions  par  des  essais  photographi- 
ques  qui,  a  c6te  de  1'aigrette  des  gaz  chauds  de  la  detonation, 
montrent  la  flamme  secondaire  globuleuse,  que  suppriment  les 
sels  alcalins. 

L'action  de  ces  sels  diminue  done  le  risque  d'inflammation  du 
grisou  ou  des  poussieres  par  les  flammes  secondaires,  dans  les  cas 
ou  celles-ci  risquent  de  se  produire;  les  sels  alcalins  re*duisent  en 
outre  la  probabilite  d'inflammation  des  melanges  grisouteux 
explosifs,  en  1'absence  de  toute  flamme  secondaire.  On  entrouvera 
la  preuve  dans  le  tableau  suivant  de  charges  limites  obtenues 
avec  des  cartouches  de  30  millimetres  dans  un  canon  de  40  milli- 
metres de  diam£tre. 


Designation 
de  1'explosif 

Charge  limite,  en  grammes 

sans  salpetre 

avec  salpfitre 

Grisou-naphtalite  couche  
Grisou-naphtalite  roche 

660 
240 
100 

>840 
>670 
220 

Grisou-dynamite  roche  

En  presence  des  poussieres,  les  sels  alcalins  n'ont  pas  d'in- 
fluence  nette;  c'est  une  preuve  que  le  me*canisme  d'inflammation 
est  different. 

2°  Influence  de  la  densite*  de  1'explosif. 

On  sait  que  la  densite*  d'encartouchage  influe  sur  le  mode  de 
detonation.  Pour  un  diametre  de  cartouche  donne*,  la  vitesse 
de  detonation  varie  avec  la  densite*  de  1'explosif;  elle  croit  d'abord 
regulierement  avec  cette  densite*  jusqu'a  une  certaine  densit^ 


136          Original  Communications:  Eighth  International        [VOL. 

limite,  &  partir  de  laquelle  la  vitesse  de  detonation  decroit  rapide- 
ment,  jusqu'a  ce  que  Pexplosif  ne  detone  plus. 

Nous  avons  constate  que  la  densite  d'encartouchage  avait 
egeiement  une  grande  influence  sur  le  risque  d'inflammation  du 
grisou. 

Ainsi  la  grisou-dynamite  roche,  tir^e  en  cartouches  de  30  m/m, 
dans  un  canon  de  40  m/m.,  a  donne*  une  charge  limite  de  150 
grammes  pour  les  densites  comprises  entre  1,  4  et  1,  5  et  une 
charge  limite  supeYieure  a  725  grammes  pour  les  densites  in- 
ferieures  a  1,  4  et  notamment  pour  celles  comprises  entre  1,  3  et 
1,  4.  II  est  remarquable  qu'une  aussi  faible  variation  de  densite 
entraine  une  aussi  grande  difference  dans  la  charge  limite; 
cette  difference  ne  peut  d'ailleurs  aucunement  s'expliquer  par 
la  ^valeur  le*gerement  plus  grande  de  la  densite*  de  chargement, 
dans  le  cas  de  la  plus  forte  densite  d'encartouchage;  car  une  charge 
limite  presque  aussi  basse  (200  grammes)  a  e"te  obtenue  avec  des 
cartouches  de  20  m/m.  de  diametre  qui,  a  la  densite*  de  1,  4  a 
1,  5,  re*alisaient,  en  raison  de  leur  diametre  re*duit,  une  densite 
de  chargement  beaucoup  plus  faible  que  les  echantillons  com- 
paratifs.  Les  essais  calorimetriques  montrent  d'ailleurs  que 
les  variations  observers  dans  les  charges  limites  ne  correspondent 
pas  a  des  differences  notables  dans  les  chaleurs  d'e*gagees. 

Des  resultats  analogues  ont  e*te*  obtenus  avec  les  grisou-naph- 
talites  couche  et  roche. 

On  a  trouve*  chaque  fois  une  certaine  densite  limite  se*parant 
des  densit^s  fortes  ou  la  charge  limite  est  relativement  basse,  et 
des  densites  plus  faibles  ou  la  charge  limite  est  relativement 
e*leve"e,  pour  des  conditions  de  tir  determinees.  La  valeur  de 
cette  densite  limite  varie  suivant  la  nature  de  Pexplosif  et  son 
degre  d'humidite;  elle  s'est  trouvee  parfois,  mais  non  toujours, 
coincider  avec  la  densite  limite  au  point  de  vue  de  la  vitesse  de 
detonation;  comme  elle  n'est  pas  eioignee  des  densites  usuelles 
d'encartouchage,  de  legeres  variations  dans  la  fabrication  des 
cartouches  ou  dans  le  degre  d'humidite  sont  capables  de  modifier 
profondement  les  charges  limites  de  securite,  soit  dans  les  condi- 
tions des  essais,  soit  peut-etre  aussi  dans  les  conditions  du  tir 
reel. 

3°  Influence  du  degre  de  trituration. 


rv]  Congress  of  Applied  Chemistry  137 

Les  explosifs  usuels  sont  formes  de  plusieurs  composes  qui  sont 
supposes  reagir  les  uns  sur  les  autres  au  moment  de  la  detonation. 
Si  le  melange  n'est  pas  tout  a  fait  intime  et  parfait,  diverses 
anomalies  peuvent  se  produire;  si  la  detente  est  tre"s  rapide,  il 
pent  arriver  que  certaines  reactions  ou  decompositions  n'aient 
pas  le  temps  de  se  produire;  dans  d'autres  cas,  ou  les  gaz  sont 
mieux  maintenus  en  contact,  on  pourra  avoir  des  reactions  plus 
completes,  mais  d'une  dure*e  prolongee. 

Ces  causes  peuvent  agir  differemment  suivant  les  conditions 
du  tir  et  le  me*canisme  de  1'inflammation;  une  mauvaise  tritura- 
tion  a  recuie  la  charge  limite  d'une  grisou-naphtalite  couche 
tiree  en  cartouches  suspendues,  tandis  qu'elle  a  fortement  abaisse 
la  charge  limite  d'une  kohlencarbonit  tir^e  dans  le  mortier  d'acier 
en  presence  des  poussieTes. 

4°  Influences  diverses. 

D 'autres  causes  concernant  la  constitution  chimique  et  physique 
de  Pexplosif,  notamment  le  grenage,  le  degre*  d'humidite*,  influent 
sur  la  securite;  nous  ne  nous  attarderons  pas  a  discuter  ces  effets 
qui  sont  d'ailleurs  generalement  connus. 

V.     Influences  relatives  aux  conditions  de  tir. 

1°  Influence  du  diam£tre  du  canon  et  de  la  densite  de  charge- 
ment. 

Cette  double  influence  a  e*te*  constatee  bien  des  fois  dans  les 
galeries  d'essais;  elle  a  donne  lieu,  a  la  Station  d'essais  de  LieVin, 
a  de  nombreuses  recherches,  dans  le  detail  desquelles  il  serait 
trop  long  d'entrer.  II  suffira  de  rappeler  que  d'une  maniere 
generale  les  charges  limites  sont  d'autant  plus  basses  que  le 
diametre  de  P  dme  du  canon  est  plus  faible,  et  que  la  densite  de 
chargement  est  plus  forte. 

Toutefois,  en  presence  du  grisou,  les  conditions  les  plus  dures 
sont  realise*es  quand  la  cartouche  est  librement  suspendue  au 
sein  du  melange  explosif;  la  grisou-dynamite  couche  dont  la 
detonation  dans  ces  conditions  est  particulierement  incomplete, 
n'enflamme  generalement  le  grisou  qu'a  partir  de  250  grammes; 
les  autres  explosifs  essayes  renflamment  a  partir  de  100  ou  50 
grammes;  c'est  notamment  le  cas  pour  la  kohlencarbonit. 

2°  Influence  de  la  nature  des  enveloppes. 


138  Original  Communications:  Eighth  International        [VOL. 


L'enveloppe  des  cartouches,  si  elle  est  composee  de  corps  suscep- 
tibles  de  re*agir  chimiquement  sur  les  produits  gazeux  de  la  deto- 
nation, participe  aux  reactions  explosives. 


Conditions  de  1'essai 

02 

CO2 

CO 

H2 

CH< 

Observations 

Decomposition  theorique.  .  .  . 

Cartouche  plac£e  dans  le 
canon  d'acier,  sans  aucune 
enveloppe  

% 
11,4 

I'1 

0  Q 

% 

21,9 

19,0 
a 

oo  o 

% 

0,0 

0 
a 
4  1 

% 

0,0 

0 

a 

1    A 

% 

0,0 

4  essais 
8  prises  de 

Memes  dispositions,  mais 
avec  leger  bourrage  

0 

19,1 

^fc,-1 

1,4 
A, 

1,0 

0 

0 

A 

gaz. 
2  essais 

Cartouche  entouree  d'une 
enveloppe  de  papier  d'ami- 
ante  (sans  bourrage)  

a 
3,0 

0,1 

a 

Q  Q 

a 
22/2 

18,0 
a 
20  *> 

4,8 
1,0 

a 
0,5 

0,6 

1,3 

gaz. 

2  essais 
3  'prises  de 

Cartouche  entouree  d'un 
papier  paraffin^  

O,O 

-2,9 
a 

13,3 

5,3 
a 

1,7 
a 

5,0 
a 

3  essais 

M6mes  dispositions,  mais 
avec  leger  bourrage  

Cartouche  entouree  d'une 
feuille  d'  aluminium  (sans 
bourrage) 

-0,8 

T 

-0,9 

-2,9 
a 
-0  8 

19,5 

18,3 
a 
23,1 

19,8 
a 
21  0 

13,1 

¥ 

9,6 
°/ 

1     1 

6,2 

0,6 
a 
1,2 

0,7 
a 
1  *> 

8,6 

3,6 
a 
4,5 

gaz. 

2  essais 
3  p-.  de 
gaz. 

1  essai 
2  prise  ;  de 

Cartouche  entouree  d'une 
feuille  d'etain  

—  u,o 

-2,0 
a 

V 

^J-1- 

1,8 
a 

X,«J 

g<t/i. 

1  essai 
2  pr    de 

Cartouche  entour6e  de  papier 
paraffin^  et  de  20  gr.  de  char- 
bon  pulverulent  

-0,8 

-0,9 
a 
1  0 

15,2 
H.O 

14,1 

2,3 

15,5 
a 
19,9 

12,0 
a 
15,7 

4,8 
a 
7,1 

gaz. 

1  essai  ^ 
2  prises'de 
gaz. 

Cartouche  entouree  d'une 
feuille  detain  et  de  20  gr.  de 
charbon  pulverulent  

-1,75 
a 
-0,5 

13,3 
a 
15,1 

14,9 
a 
21,5 

20,0 
a 

46,0 

8i 

5,8 

1  essai 
2  prises'de 
gaz. 

L'analyse  des  gaz  de  la  detonation,  dans  le  tir  au  canon, 
lev^s  comme  il  a  ete*  dit,  en  apporte  une  premiere  preuve.  Le 
tableau  suivant  donne,  a  titre  d'exemple,  la  composition  de  ces 
gaz  pour  divers  tirs  de  grisou-naphtalite  roche;  parmi  les  gaz 
recueillis  se  trouve  du  protoxyde  d'azote,  N2O,  qui  n'a  generale- 


iv]  Congress  of  Applied  Chemistry  139 

ment  pas  e*te  dose  et  dont  la  teneur  est  de  Pordre  de  grandeur 
de  3%:  il  doit  se  former  aussi  du  bioxyde  d'azote,  NO,  qui  se 
transforme  en  peroxyde,  NO,2  aux  depens  de  Poxygene  disponible, 
provenant  notamment  de  Fair  du  tube  de  prise  de  gaz;  c'est 
pourquoi,  lorsqu'on  corrige  les  resultats  bruts  d'analyse  en  de- 
duisant  le  volume  de  cet  air,  on  trouve  souvent  pour  Poxygene 
des  nombres  negatifs.  Le  peroxyde  d'azote  se  dissout  dans  1'eau 
de  condensation  et  Peau  de  la  cuve;  on  y  retrouve  des  nitrites  et 
nitrates. 

Ce  tableau  prouve  que  non  seulement  les  proportions  de  gaz 
degages  ne  sont  pas  du  tout  celles  que  donnerait  la  decomposition 
complete,  mais  que  de  plus  elles  different  dans  de  larges  propor- 
tions suivant  la  nature  de  Penveloppe;  on  remarquera  en  particu- 
lier  les  fortes  teneurs  en  gaz  combustibles,  quand  Pexplosif  est 
entoure'  de  paraffine  et,  surtout,  de  charbon. 

Des  essais  photographiques  montrent  que  ces  gaz  combustibles 
peuvent  s'enflammer  en  se  me*langeant  a  Pair  ambiant;  cette 
flamme  secondaire  est  parfaitement  distincte,  dans  Pespace  et 
le  temps,  de  la  breve  aigrette  incandescente  que  produisent  habi- 
tuellement  les  gaz  de  la  detonation  en  sortant  du  canon;  elle  est 
particulierement  volumineuse  lorsqu'il  y  a  du  charbon  autour 
de  Pexplosif,  et  de*passe  parfois  1  m  80  pour  100  grammes  d'ex- 
plosif. 

Ces  flammes  secondaires  constituent  Pun  des  me'canismes 
possibles  de  Pinflammation  du  grisou  ou  des  poussi&res;  la  charge 
limite  s'abaisse,  suivant  la  nature  de  Penveloppe,  jusqu'a  la  charge 
a  partir  de  laquelle  se  produisent  les  flammes  secondaires,  dans 
les  conditions  du  tir.  Le  tableau  suivant  donne  une  idee  de 
ces  variations. 

Les  charges  limites  varient  done  conside*rablement  suivant  la 
nature  de  Pentourage  immediat  des  cartouches;  en  particulier 
le  tir  au  canon  d'acier,  tel  qu'on  le  pratique  d'ordinaire  pour  la 
determination  des  charges  limites  ne  peut  donner  qu'une  idee 
tres  imparfaite  de  la  valeur  de  Pexplosif  lorsqu'on  le  tire  dans  un 
trou  de  mine  dont  les  parois  sont  charbonneuses. 

II  est  possible  que  Pintervention  de  Pacier  du  canon  dans  la 
reaction  cre*e  de  m£me  une  difference  syste"matique  entre  les 
conditions  de  tir  des  essais  et  celles  des  tirs  re*els  au  rocher. 


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Original  Communications:  Eighth  International       141 

Dans  un  autre  ordre  d'idees,  on  remarquera  le  relevement  des 
charges  limites  en  presence  des  poussieres,  lorsqu'on  exagere  les 
quantity's  de  paraffine  et  charbon  environnant  les  cartouches;  il 
est  done  possible  d'e>iter  T^cueil  des  flammes  secondaires  en  se 
plagant  du  c6te*  des  limites  superieures  d'inflammabilite;  mais 
il  est  sans  doute  preferable,  du  moment  que,  dans  le  tir  au  charbon, 
on  ne  peut  garantir  Pabsence  de  gaz  combustibles,  d'agir  sur  la 
composition  de  1'explosif  pour  diminuer  le  risque  que  ces  gaz 
ne  s'enflamment,  en  utilisant,  par  exemple,  les  propriete*s  des 
sels  alcalins. 

3°  Influence  de  la  longueur  du  canon. 

La  charge  limite  depend  non  seulement  du  diam£tre  du  canon, 
comme  il  a  ete  souvent  ve*rifie,  mais  aussi  de  sa  longueur.  Dans 
un  canon  de  55  millimetres  de  diametre  inte*rieur  et  1  m  20  de 
longueur  la  charge  limite  de  la  grisou-dynamite  roche  salpetre"e 
entoure*e  de  papier  ordinaire,  est  de  275  grammes;  mais  si  Ton 
reduit  la  longueur  du  canon  en  bourrant  le  fond  avec  de  Pargile, 
la  charge  limite  croit  progressivement  comme  le  montre  le  tableau 
suivant : 

Longueur  du  canon. .     1  m  20     1,15       1,00       0,60     metre 
Charge  limite 275          375        450        525     grammes. 

Cette  importante  variation  de  charge  limite,  qui  va  presque  du 
simple  au  double,  n'est  pas  imputable  a  la  variation  de  position 
des  cartouches  par  rapport  a  1'orifice;  car  si,  laissant  celles-ci  sur 
les  0  m  60  voisins  de  Porifice,  comme  dans  les  essais  qui  donnerent 
la  charge  limite  de  525  grammes  on  rend  au  canon  sa  longueur 
entiere  de  1  m  20,  on  retrouve  la  charge  limite  initiale  de  275 
grammes.  Les  cir Constances  qui  elevent  la  charge  limite  sont 
done  celles  pour  lesquelles  une  plus  grande  surface  de  me*tal  est 
au  contact  des  gaz  de  la  detonation  et  Ton  est  d'autant  plus  con- 
duit a  songer  a  la  participation  probable  des  parois  a  la  reaction, 
que  Ton  constate  dans  la  chaudiere  calorimetrique,  un  certain 
accroissement  du  nombre  de  calories  degagees  (20%,  dans  le  cas 
etudie,  pour  la  grisou-dynamite  roche  tire*e  dans  un  meme  canon 
de  55  millimetres  ayant  1  m  ou  0  m  50  de  profondeur).  Mais 
on  ne  peut  pas  faire  abstraction  d'autres  causes  de  difference 


142  Original  Communications:  Eighth  International        [VOL. 

dans  le  mode  de  detente  des  gaz,  les  pressions  exercees  sur  le 
milieu  ambiant  et  la  duree  de  la  flamme. 

4°  Influence  du  bourrage. 

II  est  bien  connu  que  le  bourrage  augmente  la  charge  limite. 
Des  Etudes  comparatives  ont  ete  faites  sur  Pinfluence  relative 
des  divers  modes  de  bourrage  dans  Pessai  au  canon,  bourrage 
interieur  selon  la  pratique  courante,  bourrage  exterieur  selon  la 
formule  proposed  par  les  experimentateurs  beiges  a  titre  de  sur- 
croit  de  garantie.  Les  essais  execute's  en  presence  des  poussieres 
montrent  que  les  divers  modes  de  bourrage,  compares  a  poids 
egal,  se  classent  comme  suit  dans  Pordre  d'efficacite  decroissante : 
bourrage  interieur  au  contact  de  la  charge,  bourrage  interieur 
distant  de  la  charge,  bourrage  exte*rieur  obstruant  Porifice,  bour- 
rage exterieur  en  tas  devant  Porifice,  mais  ne  Pobstruant  pas. 
II  faut  deux  a  quatre  fois  plus  de  bourre  sous  forme  de  bourrage 
exterieur  que  sous  forme  de  bourrage  interieur,  pour  determiner 
un  m£me  recul  de  la  charge  limite;  mais  la  quantity  de  bourre 
que  Pon  peut  accumuler  devant  un  trou  de  mine  n'est  pas  limitee 
comme  celle  que  Pon  peut  introduire  dans  le  trou,  et  si  Pon  com- 
bine les  deux  systemes,  ainsi  que  Pentendent  expressement  les 
promoteurs  du  bourrage  exterieur,  il  n'en  peut  re*sulter,  dans  le 
cas  ge*ne*ral,  qu'un  se*rieux  appoint  de  se*curite. 

5    Deflagrations  fusantes. 

Les  explosifs  a  Pazotate  d'ammoniaque  etudie"s  ci-dessus, 
grisou-dynamites  et  grisou-naphtalites,  ne  paraissent  a  priori 
susceptibles  que  de  deux  modes  de  decomposition:  la  detonation 
amorce*e  au  fulminate  et  Pexplosion  ou  combustion  sous  forte 
pression  (essai  a  la  bombe);  a  la  pression  atmospherique  ces 
explosifs  ne  propagent  pas  la  flamme.  Or,  on  a  signale  que,  dans 
la  mine,  certains  trous  de  mine  au  charbon,  ayant  mal  travaille, 
donnaient  lieu  a  une  flamme  rouge  persistant  au  fond  du  trou, 
avec  un  bruit  particulier  assimile  a  celui  de  la  graisse  bouillante, 
et  un  de"gagement  abondant  de  fumees  acres.  La  "deflagration 
fusante"  ainsi  caracterisee  peut  durer  une  ou  plusieurs  minutes; 
une  duree  superieure  a  une  demi-heure  aurait  meme  ete  const atee. 
Ce  ph^nomene  risque  de  passer  inapergu  s'il  est  d'usage  d'attendre 
quelque  temps  avant  de  revenir  au  chantier;  aussi  est-il  peut-etre 
plus  frequent  qu'on  ne  le  suppose  parfois;  il  constitue  un  danger 


iv]  Congress  of  Applied  Chemistry  143 

se*rieux  dans  les  mines  grisouteuses.  II  n'a  jamais  e*te*  constate* 
a  1'occasion  de  trous  fore's  dans  le  rocher. 

Les  essais  ont  montre*  que  la  deflagration  fusante  e*tait  due  au 
voisinage  de  la  paroi  de  charbon;  on  a  reproduit  le  phenomene 
en  allumant  avec  une  flamme  un  melange  d'explosif,  ou  simple- 
ment  d'azotate  d'ammoniaque  et  de  charbon;  il  n'est  meme  pas 
necessaire,  pour  entretenir  la  combustion  fusante,  que  le  melange 
soit  preexist  ant;  il  suffit  de  faire  tomber  de  temps  en  temps  des 
fragments  de  charbon  sur  la  cartouche  en  train  de  fuser;  on  a 
meme  pu,  au  moyen  d'un  amorgage  approprie,  realiser  des  de*- 
flagrations  fusantes  dans  le  canon  d'acier,  ou  la  cartouche  d'ex- 
plosif  avait  etc*  entoure*e  de  charbon  pulverulent. 

Ce  dangereux  phenomene,  qu'il  faut  craindre  avec  tous  les 
explosifs  a  1'azotate  d'ammoniaque,  ne  peut  survenir  qu'a  la  suite 
d'un  rate  de  transmission  de  la  detonation.  II  convient,  pour 
1'eviter,  de  curer  soigneusement  le  trou  de  mine  et  de  mettre  les 
cartouches  bien  en  contact.  II  faut  en  outre  que  1'explosif  ait 
une  aptitude  suffisante  a  la  transmission  de  la  detonation. 

On  est  ainsi  conduit  a  etudier  la  question  de  1'amorc.age  des 
explosifs  dans  ses  rapports  avec  la  question  de  la  transmission  de 
la  detonation  de  la  cartouche  amorce  aux  cartouches  suivantes. 

Les  distances  de  transmission  sont  mesure'es,  pour  plus  de  com- 
modite*,  sur  plaques  de  plomb;  on  a  d'ailleurs  verifie  que  pour 
le  grisou-naphtalite  couche  les  distances  de  transmission  &taient 
les  memes  dans  le  canon. 

On  a  constate  que  la  distance  maximum  de  transmission  e*tait 
notablement  plus  faible  a  partir  de  I'extremit4  de  la  cartouche 
amorce  oil  Ton  a  introduit  la  capsule  de  fulminate,  qu'a  partir  de 
Textremite  opposee;  on  trouve,  par  exemple,  pour  les  naphtalites 
couche,  2  centimetres  d'un  cote*,  5  centimetres  de  1'autre.  II  y  a 
done  inte*ret,  pour  la  bonne  transmission  de  la  detonation,  a 
pratiquer  1'amorc.age  direct  (amorce  cote  du  bourrage)  plutot  que 
1'amorc.age  inverse  (amorce  cote  de  la  derniere  cartouche). 

C'est  la  distance  a  1'amorce  fulminante  qui  importe  plutot  que 
le  sens  de  transmission  de  la  detonation;  en  amor  gage  direct,  une 
cartouche  longue  transmet  mieux  qu'une  courte;  si  la  de*tonateur 
e*tait  au  milieu  de  la  cartouche,  la  transmission  se  ferait  aussi  bien 
par  les  deux  extremity's. 


144  Original  Communications:  Eighth  International        [VOL. 

6°  Le  cordeau  detonant. 

M.  Lheure,  Ingenieur  des  Poudres  et  Salpetres,  a  imaging  de 
plager,  sur  toute  la  longueur  de  la  charge,  un  cordeau  detonant; 
ce  dispositif  supprime  les  rate's  de  transmission  aux  intervalles 
de  cartouches  et  accroit  dans  une  certaine  mesure  la  densite 
limite  a  partir  de  laquelle  commencent  les  detonations  incom- 
pletes.  Ce  sont  d'incontestables  avantages. 

Mais  ce  qui  est  vrai  des  enveloppes  Pest  e*galement  du  cordeau 
detonant:  les  produits  de  la  detonation  de  1'explosif  contenu  dans 
le  cordeau,  et  meme  le  plomb  qui  en  constitue  1'enveloppe  peuvent 
participer  aux  reactions  explosives  de  telle  sorte  qu'au  point  de 
vue  des  chaleurs  degagees  le  resultat  est  alors  le  meme  que  si  les 
constituants  du  cordeau  avaient  e*te*  intimement  meles  aux  car- 
touches. Ces  combustions  peuvent  £tre  parfois  suffisamment 
rapides  pour  accroitre  notablement  la  puissance  des  explosifs 
amorce's  au  cordeau. 

L'influence  de  cet  amorgage  sur  les  charges  limites  au  canon  a 
ete  etudiee  sur  des  cartouches  de  grisou-naphtalite  couche  com- 
prime'e.  II  a  fallu  faire  des  essais  avec  bourrage  afin  que  le  risque 
d'inflammation  resultant  de  la  detonation  du  cordeau  en  atmo- 
sphere grisouteuse  ne  risquat  pas  de  marquer  1'effet  du  cordeau 
sur  1'explosif  et  sur  sa  plus  ou  moins  grande  aptitude  a  enflammer 
le  grisou.  II  est  apparu  une  difference  systematique  indiquant 
que  le  cordeau  augmente  le  risque  d'inflammation;  mais  la  diffe- 
rence est  faible  et  1'on  retablit  1'egalite  de  risque  en  ajoutant 
seulement  deux  centimetres  de  bourrage.  II  semble  bien  que, 
dans  les  conditions  de  ces  essais,  les  combustions  secondaires  ont 
ete  peu  importantes. 

CONCLUSION 

Ce  rapide  apergu  de  quelques  uns  des  aspects  de  la  question 
des  explosifs  de  surete,  telle  qu'elle  est  etudiee  a  la  Station  d'essais 
de  Lievin,  montre  toute  la  complexite  du  probleme.  Les  formules 
simples  par  lesquelles  on  a  coutume  de  definir  les  explosifs  de 
surete,  aussi  bien  Fancienne  formule  theorique  du  reglement 
frangais  que  les  formules  pratiques  usitees  a  Tetranger,  apres 
avoir  rendu  de  tr£s  grands  services,  auront  sans  doute  bientot 
fait  leur  temps;  deja,  en  France,  la  nouvelle  reglementation  cesse 


rv]  Congress  of  Applied  Chemistry  145 

de  fixer  une  regie  uniforme  pour  caracte*riser  les  explosifs  de 
surete* ;  il  est  reserve*  a  la  Commission  du  grisou  de  juger,  dans 
chaque  cas,  des  epreuves  a  faire  subir  aux  nouveaux  explosifs 
proposes,  e*preuves  qui  peuvent  dependre  du  type  d'explosif  et 
qui  eVolueront  avec  les  progress  de  nos  connaissances.  La  Station 
d'essais  de  LieVin,  a  qui  incombe  le  soin  de  l'expe*rimentation, 
s'attache  a  faire,  de  chaque  explosif,  une  etude  aussi  complete 
que  possible,  en  variant  les  conditions  d'essais  et  examinant  les 
divers  risques. 

II  est  avant  tout  desirable  que  Ton  poursuive,  dans  les  diverses 
Stations  d'essais,  des  etudes  rationnelles  et  systematiques,  dans  le 
but  de  mieux  connaitre  les  divers  mecanismes  d'inflammation  et 
le  role  des  diverses  proprie"tes  de  Pexplosif  dans  chacun  de  ces 
me*canismes.  La  Station  d'essais  de  LieVin  s'est  oriente*e  resolu- 
ment  dans  cette  voie  des  recherches  generates  et  s'est  outill^e  en 
consequence;  elle  acquiert  de  jour  en  jour  la  conviction  plus 
intime  que  les  classements  actuels  d'explosifs  de  surete  sont 
fortement  sujets  a  critique,  et  que  les  critiques  ne  pourront  etre 
levies,  que  de  serieux  progres  ne  pourront  etre  realises  que  grace 
a  une  ^tude  scientifique  approfondie  de  la  question. 


Published  by  permission  of  the  Director  of  the  Bureau  of  Standards 


ON  A  MODIFIED  FORM  OF  STABILITY  TEST 

BY  H.  C.  P.  WEBER 
Bureau  of  Standards,  Washington,  D.  C. 

Some  time  ago  an  investigation  on  the  stability  of  nitrocellulose 
plastics  was  undertaken  at  the  Bureau  of  Standards  and  the 
question  of  the  stability  of  these  materials  at  normal  and  elevated 
temperatures  was  one  of  the  questions  studied. 

One  of  the  stability  tests,  employed  in  that  investigation,  seems 
of  sufficient  interest  to  warrant  calling  attention  to  it,  especially 
since  it  does  not  seem  possible  to  carry  the  investigation  further 
at  present. 

The  papers  to  which  reference  has  been  made  in  connection 
with  this  subject  are  tabulated  at  the  end  of  this  paper  and  will 
not  be  cited  again  in  detail. 

There  is  perhaps  no  need  for  going  into  details  regarding  all 
the  various  tests  proposed.  While  there  are  many  of  them,  each 
having  its  own  particular  advantage,  only  a  few  are  at  all  generally 
applied.  The  reason  for  adding  to  their  number  is  that  while 
this  test  is  an  explosion  test,  and  therefore  simple  and  rapid,  it 
is  in  reality  a  determination  of  the  change  of  decomposition  veloc- 
ity with  rise  in  temperature  and,  as  such,  a  measure  of  stability. 

Various  investigators  have  touched  upon  the  influence  of  the 
rate  of  heating  on  the  result,  whether  it  be  in  the  explosion  tests 
or  in  methods  depending  on  the  amount  or  rate  of  gas  evolution. 
For  this  reason  the  rate  of  heating  in  the  explosion  test  is  defined 
within  certain  limits.  The  decomposition  of  nitrocellulose  is 
autocatalytic  and  when  a  certain  surrounding  temperature  is 
attained,  say  135  C0.,  nearly  all  samples  of  nitrocellulose  will 
explode  if  kept  in  surroundings  of  that  temperature  long  enough. 
The  temperature  of  the  decomposing  material  may  be  a  few  or 
many  degrees  above  135°.  In  the  investigation  of  nitrocellulose 
plastics  we  have  repeatedly  seen  differences  of  30°  and  40°  between 

147 


148  Original  Communications:  Eighth  International       [VOL. 

the  temperature  of  the  surroundings  and  of  the  sample  when  the 
substance  went  off.  The  amount  of  this  difference  depends  on 
the  mass  of  the  material  and  its  heat  conductivity,  and  on  the 
heat  conductivity  of  the  system  used  for  test.  These  factors 
enter  into  the  German  135°  test  as  well  as  into  the  ordinary  high 
temperature  explosion  test.  In  the  former  the  time  will  vary 
with  the  heat  insulation,  in  the  latter  the  explosion  temperature 
will  vary  with  the  rate  of  heating. 

The  apparatus  used  for  the  test  is  shown  in  Fig.  1.  The  heating 
bath  consists  of  a  crucible  of  iron  or  nickel,  about  10  cm.  in  dia- 
meter and  of  approximately  the  same  depth.  The  cover  is  of 
sheet  metal  about  3  mm.  thick,  with  a  flange  that  fits  snugly 
into  the  crucible  and  projects  slightly  beyond  the  rim.  One  hole 
through  the  centre  of  the  cover  is  just  large  enough  to  permit  the 
thermometer  to  pass.  Symmetrically  distributed  around  the 
centre  of  the  plate  are  8  openings  15  mm.  in  diameter.  The  heavy 
metal  supporting  tubes  are  about  4  cm.  in  length  and  about  12 
mm.  internal  diameter.  The  lower  end  of  the  tube  is  flanged  so 
that  the  tube  rests  securely  on  the  cover.  The  test  tubes  are 
about  9  cm.  long  and  must  be  of  such  diameter  that  they  will 
just  slip  freely  into  the  supporting  tubes.  A  number  of  extra 
caps  are  provided  to  cover  openings  not  intended  to  be  used  during 
the  test.  The  heating  liquid  may  be  either  paraffine,  glycerine, 
or  similar  inert  liquid  which  may  be  heated  to  200°  without  boiling 
or  fuming  strongly.1 

The  test  tubes  should  dip  about  4  or  5  cm.  into  the  heated 
liquid  so  that  their  ends  will  be  at  about  the  centre  of  the  heated 
mass  and  may  readily  be  removed  one  at  a  time  and  replaced  by 
fresh  ones.  For  each  explosion  a  clean  tube  should  be  taken. 

The  thermometer  is  supported  by  a  metal  clip  which  rests  on 
the  cover,  the  bulb  being  on  a  level  with  the  lower  ends  of  the 
test  tubes.  The  thermometer  used  was  standardized.  Since 
the  mercury  thread  projected  but  little  above  the  highly  heated 
zone  the  stem  correction  was  found  to  be  negligible.  This  should 
be  checked  with  each  apparatus  and  thermometer  for  the  various 
temperatures,  when  the  apparatus  is  put  together. 

1(rhis  form  of  apparatus  has  been  devised  by  C.  E.  Waters  in  connection 
with  work  on  lubricating  oils. 


iv] 


Congress  of  Applied  Chemistry 


149 


FIGURE  1 

The  heating  bath  is  suspended  in  a  conical  piece  of  sheet  metal 
wrapped  with  asbestos.  The  metal  shield  (Met.  Sh.)  is  cut  so 
that  the  crucible  will  hang  securely  in  the  upper  smaller  opening, 
while  its  larger  end  rests  in  the  flanged  tripod  rim.  With  this 
apparatus  and  a  small  gas  flame  it  has  been  easily  possible  to 
maintain  the  temperature  constant  for  15  or  20  minutes  within 
half  a  degree.  It  is  most  convenient  to  have  the  burner  set  so 


150  Original  Communications:  Eighth  International      [VOL. 

that  there  is  a  tendency  for  the  temperature  to  fall  and  to  use  a 
small  accessory  flame  momentarily  whenever  necessary.  With 
a  temperature  regulator  or  with  electrical  heating  the  ease  of 
manipulation  might  no  doubt  be  increased  but  this  is  a  matter 
of  detail. 

One  or  two  stop  watches1  complete  the  equipment.  When 
the  apparatus  has  attained  equilibrium  at  the  desired  temperature 
one  or  more  of  the  test  tubes  is  loaded  by  dropping  in  the  sample 
of  powder,  the  stopwatch  is  started  and  a  cork  is  dropped  into  the 
mouth  of  the  test  tube.  The  time  until  the  explosion  takes  place 
is  then  noted. 

The  grains  of  the  six  pounder  smokeless  powder  are  of  conven- 
ient size  to  use  directly.  Powders  of  larger  caliber  should  be  cut 
into  pieces  weighing  about  0.2g  each.  Each  sample  of  powder 
was  tested  at  four  temperatures,  160°,  170°,  180°,  and  200°. 
For  the  present  purpose  at  least  three  tests  were  made  at  each 
temperature  interval  and  curve  was  drawn  through  the  average 
values. 

The  following  series  on  powder  A  shows  how  closely  duplicates 
may  be  expected  to  agree: 

Max. 
Av.     Variations 

200°  1'44"  1'48"  1'44"  l'48"     l'45"     1'46"  2% 

180°  2'55"  3'06"  3' 10"  3/04//  5% 

170°  4/17//  4'30"  4'28"  4'25"  3% 

160°  14'20"  17'40"  17'34"  16'36"  14% 

In  general  the  discrepancies  appear  to  be  greater  at  the  lower 
temperatures.  This  is  to  be  expected  since  the  curves  given  further 
on  show  to  what  extent  the  influence  of  small  temperature  varia- 
tions is  magnified  in  the  region  of  160°.  Furthermore  the  irregu- 
larities are  more  pronounced  in  the  "poor"  powders. 

The  following  set  shows  what  can  be  expected  as  to  reproduci- 
bility  of  the  complete  curve.  The  sample  used  was  L  and  the 
second  test  was  made  one  month  later  than  the  first.  The  averages 
only  are  given. 

LI  have  found  the  type  of  stop  watch  with  two  second  hands,  which  may  be 
stopped  independently,  the  most  convenient  form.  With  two  of  these  at 
least  four  samples  may  be  observed  simultaneously. 


iv]  Congress  of  Applied  Chemistry  151 


200° 

180° 

170° 

160° 

I. 

1'31" 

2'18" 

3'39" 

7'n" 

II. 

1'27" 

2'31" 

*'&" 

7'30" 

The  following  table  and  Fig.  2,  give  the  results  obtained  with 
ten  samples  of  smokeless  and  two  samples  of  nitrocellulose.  The 
samples  were  obtained  through  the  Navy  Department  and  I  am 
indebted  to  the  courtesy  of  G.  W.  Patterson,  Powder  Expert  at 
Indian  Head,  for  the  selection  of  three  classes,  good,  fair,  and  poor; 
and  for  the  description  of  these  samples,  which  I  quote  for  com- 
parison with  the  explosion  periods. 

Nitrocellulose  A.  "Specially  prepared.  Heat  test,  potassium-iodide  starch, 
at  65.°5C.,  4  min.;  German  test  at  135C.,  9  min.  for  litmus  red." 

Nitrocellulose  B.  "Heat  test,  potassium-iodide  starch  at  65°.5C.,  42 
min.,  German  test  at  13°. 5C.,  38  min.,  for  litmus  red." 

Powder  Sample  A.  "Six-pounder — Diphenylamine  as  stabilizer.  German 
test  at  135°C.,  litmus  red,  2  hrs.  35  min.,  explosion  5  hrs.  plus.  Surveillance 
test  at  80°C.;  87  days;  at  65°.5C.,  307  days." 

Sample  B.  "Medium  caliber.  Diphenylamine  as  stabilizer.  German 
test  at  135°C.,  litmus  red,  2  hrs.  17  min.,  explosion  5  hrs.  plus.  Surveillance 
test  at  65.°5C.,  271  days." 

Sample  C.  "Large  caliber.  Diphenylamine  as  stabilizer.  German  test 
at  135°C.,  litmus  red  1  hr.  25  min.,  explosion,  5  hrs.  plus.  Surveillance  test 
at  65°.5C.,  245  days  plus." 

Sample  D.  "Large  caliber.  No  stabilizer.  Rosaniline  as  indicator.  Ger- 
man test  at  135°C.,  litmus  red,  2  hrs.,  explosion  5  hrs.  plus.  Surveillance  test 
at  65°.5C.,  60  days." 

Sample  E.  "Medium  caliber.  No  stabilizer.  Rosaniline  as  indicator. 
German  test  at  135°C.,  litmus  red,  1  hr.  35  min.,  explosion  5  hrs.  plus.  Sur- 
veillance test  at  65°.5C.,  74  days." 

Sample  F.  "Six-pounder.  Contains  rosaniline  and  diphenylamine.  Ger- 
man test  at  135°C.,  litmus  red,  2  hrs.  25  min.,  explosion  5  hrs.  plus.|§;Sur- 
veiUance  test  at  65°.5C.,  375  days,  at  80°C.,  64  days." 

Sample  H.  "Manufactured  in  1901.  When  last  tested  it  gave  German 
test  at  135°C.,  explosion  in  41  min.  Surveillance  test  at  65°.5C.  (1907)  79 
days." 

Sample  I.  ' 'Manufactured  about  1901.  When  last  tested  it 
gave  German  test  at  135°C.,  explosion  in  33  min.,  Surveillance 
test  at  65°.5C,  82  days." 

Samples  K  &  L.  "These  are  both  in  very  poor  condition, 
giving  only  one  day  Surveillance  test." 


152  Original  Communications:  Eighth  International      [VOL. 


FIGURE  2 


IV] 

Congress  of  Applied 

Chemistry 

153 

The  explosion  periods  obtained  on  these  samples  are  as  follows. 
The  value  underscored  is  the  average  value  : 

EXPLOSION  PERIODS 

200°C. 

180°C. 

170°C. 

160°C. 

Nitrocellu-    33" 

5'20" 

over  30' 

over  30' 

lose      A.       58" 

611" 

37" 

6'56" 

43" 

619" 

B            33" 

4'06" 

16' 

over  30' 

42" 

5'55" 

17'30" 

34" 

6'06" 

16'45" 

36" 

5'22" 



Powder       1'44" 

1'45" 

2'58" 

4'30" 

14'20" 

A         1'48" 

1'46" 

3'06" 

417" 

17'40" 

1'44" 



310" 

4'28" 

17'34" 

1'48" 

3'04" 

4'25" 

16'36" 

B         1'54" 

1'41" 

3'37"       3'27" 

5'23"       5'44" 

14'20" 

1'15" 

1'37" 

3'54"       3'57" 

5'26"       6'02" 

13'45" 

1'65" 

1'27" 

3'44"       3'44" 

5'36"       5'53" 

17'  7" 

1'32" 

1'25" 

5'28"       5'57" 

14'57" 

I  /qq// 

1  'W 

J.  OO 

J-   OU 

168° 

C         2'04" 

4'05" 

617" 

17'45" 

2'04" 

315" 

6'28" 

18'25" 

210" 

4'50" 

6'55" 

1818" 

2'06" 

4/05" 

6'34" 

18'09" 

4/20" 

615"       7'00" 

D         1'45" 

2'10" 

4'03" 

5'53"       6'50" 

19' 

1'47" 

2'30" 

4'08" 

5'57"       6'56" 

26'49" 

2' 

2' 

410" 

6'             6'56" 

28'30" 

1'58" 



24'46" 

172°         171° 



E         1'35" 

210" 

3'55" 

610" 

1015" 

2'10" 

210" 

4'06" 

5'58" 

10'24" 

210" 

418" 

6'08" 

10'29" 

2'05" 

4'06" 

6'05" 

10'23" 

F          1'40" 

1'45" 

2'47" 

3'33" 

1516" 

1'41" 

i'38" 

2'45" 

3'23r/ 

15'47" 

1'48" 

1'43" 

2'49" 

3'31" 

17'40" 

1'45" 



2'47" 

3'29" 

1614" 

154  Original  Communications:  Eighth  International        [VOL. 


EXPLOSION    PERIODS 

H 

115" 

1'38" 

3'32" 

4'45" 

6'47" 

1'29" 

1'22" 

3'35" 

417" 

6'48" 

110" 

1'28" 

3'28" 

4'44" 

6'50" 

i  'i  e;" 

o/oo// 

AfOKff 

R'AQ" 

I 

1  1O 

2'04" 

2'05" 

O  d£ 

O  1o 

3'05" 

3'50" 

613" 

210" 

2'05" 

3'05" 

3'49" 

6'00" 

2'02" 

2'04" 

3'20" 

3'56" 

617" 

2'00" 



310" 

3'50" 

610" 

K 

2'05" 

1'50" 

3'29" 

5'55" 

1112"     12'28" 

2'05" 

1'52" 

3'30" 

5'22" 

11'8"       13' 

214" 

2'04" 

3'50" 

615" 

12'38"     11'54" 

217" 



3'36" 

5'51" 

ll'OO"    

L 

1'31" 

1'30" 

213" 

3'38" 

1'22" 

1'40" 

218" 

3'33" 

1'27" 

1'31" 

2'22" 

3'47" 

1'35" 

218" 

3'39" 

K  at  183°  3'20",  3'29";  at  160°  12'43",  13'20" 

F  at  178°  3'00",  313" 

A  at  199°  1'47";  at  198°,  1'53";  at  197°  1'52";  at  195  Ir56"  at  193.5  212. 

The  curves  embodying  these  results  are  given  in  Fig.  2.  The 
curve  marked  "theoretical  curve"  is  obtained  on  the  assumption 
that  the  reaction  velocity  doubles  for  every  10°C.  While  the 
curves  obtained  from  the  explosion  periods  are  of  the  same  general 
type,  it  is  apparent  that  the  relation  is  not  so  simple  as  that  shown 
by  the  "theoretical  curve."  What  influence  the  stabilizer  has 
upon  the  direction  of  the  curves  it  is  difficult  to  say  with  the  data 
at  hand.  It  does  not  follow  that  the  stabilizer  will  affect  the 
explosion  test  in  the  same  manner  as  it  does  the  heat  test  or  the 
surveillance  test.  The  stabilizer,  while  it  removes  the  products 
of  decomposition,  may  of  itself  act  as  a  positive  or  negative  cata- 
lyzer. If  the  decomposition  be  considered  as  the  dissociation  of  an 
ester,  the  presence  of  a  substance  removing  the  products  of  de- 
composition will  increase  the  rate.  This  has  been  noticed  by  Mit- 
tasch1  for  nitrocellulose  with  various  basic  additions  and  has  been 
confirmed  by  myself  in  the  case  of  pyroxyline  plastics  containing 
zinc  oxide, 
cit. 


iv]  Congress  of  Applied  Chemistry  155 

That  the  curves  do  actually  represent  the  stability  of  the  powder 
with  changing  temperature  and  are  not  accidental  is  shown  by 
the  reproducibility  of  the  various  points  along  the  curve,  as 
shown  in  the  table;  by  the  fact  that  the  curve  having  been  deter- 
mined by  four  points,  determinations  made  at  varying  tempera- 
tures are  found  to  fall  on  the  curve;  and  by  the  fact  that  the  com- 
plete curve  can  be  reproduced  at  widely  varying  intervals.  See 
curves  I/  and  L".  The  curves  are  undoubtedly  characteristic 
for  the  sample.  The  deviations  for  individual  points  are  not 
large  enough  to  affect  the  general  trend  of  the  curve.  What 
temperatures  are  chosen  must  probably  be  left  to  individual 
requirements.  190°  would  perhaps  be  preferable  to  200°.  At 
150°  we  should  have  the  apparent  advantage  that  the  differences 
between  various  samples  become  greater  and  the  disadvantage 
that  the  test  becomes  slower  and  the  results  are  more  subject  to 
accidental  influences.  The  bend  of  the  curve  between  180°C.  and 
160°C.  is,  perhaps,  its  most  characteristic  portion. 

The  curves  fall  into  three  distinct  groups  for  the  samples  tested, 
corresponding  to  their  general  classification  of  good,  fair,  and 
bad.  The  stable  powders  have  a  pronounced  bend,  while  the 
ratio  of  explosion  periods  at  200°  and  160°C.  is  at  least  2:9.  In 
the  unstable  samples  this  ratio  falls  as  low  as  2:3,  and  the  points 
do  not  fit  a  smooth  curve  so  well.  The  curves  for  the  two  samples 
of  raw  nitrocellulose  are  somewhat  peculiar,  being  much  flatter 
and  corresponding  more  nearly  to  the  theoretical  curve. 

The  powders  do  not  always  fall  in  exactly  the  same  order  by 
this  explosion  test  as  they  do  by  the  surveillance  or  the  heat  test, 
but  I  think  this  is  true  to  the  same  extent  for  the  135°  German 
explosion  test  and  the  ones  mentioned.  This  appears  by  com- 
parison of  the  customary  tests  on  samples  D  and  H. 

D.  German  test  135°  Litmus  red  2  hrs.,  explosion  5  hrs.;  sur- 
veillance 60.  H.  German  test;  explosion  41  min.;  surveillance  79. 

From  the  results  given  it  is  evident  that  one  explosion  tempera- 
ture, even  if  time  is  considered,  does  not  give  much  information 
while  the  determination  of  the  characteristic  curve  does  yield 
definite  and  specific  information. 

On  account  of  the  complexity  of  the  conditions  the  test  can 
hardly  be  expected  to  tell  all  that  is  to  be  known,  but  I  believe 
that  with  sufficient  data  it  may  even  be  made  to  throw  some 


156          Original  Communications:  Eighth  International 

light  on  the  actual  effect  of  the  stabilizer  on  the  natural  decompo- 
sition velocity  of  the  powder,  as  distinguished  from  the  length 
of  time  before  the  decomposition  products  become  noticeable. 
The  proposed  method  gives  more  accurate  determinations  of 
the  explosion  temperature  than  the  method  of  heating  with  rising 
temperature.  It  gives  a  better  comparison  of  the  relative  stability 
of  explosive  substances.  The  test  is  in  effect  a  determination  of 
the  rate  of  change  of  decomposition  velocity  with  change  of  tem- 
perature and  is  as  such  characteristic  for  each  sample. 

LITERATURE  REFERENCES 

Aspinwall. — Stability  Tests  for  Smokeless  Powder  and  Nitro-explosives. 
Jour.  Soc.  Chem.  Ind.,  21,  687. 

Bergmann  &  Junk. — Stability  of  Nitrocellulose.  Z.  Ang.  Chem.  17, 17, 982, 
1018,  1074. 

Cullen. — Note  on  the  so-called  "Heat  Test"  for  Explosives.  Jour.  Soc. 
Chem.  Ind.,  20,  8.  * 

Escales.-^Stability  of  Nitrocellulose.  Zeit.  Angew.  Chem.  18,  940.  Meth- 
ods for  Testing  Stability  of  Explosives  in  Various  Countries.  Z.  ges.  Schiess- 
und  Sprengstoffwesen,  5,  21,  72,  210. 

Finzi. — Ignition  Points  of  Nitrocellulose  and  Smokeless  Powders.  Gazz. 
Chim.  Ital.,  39, 1,  549. 

Jacque". — German  Railway  Administration:  Tests  and  Regulations  of  the. 
Z.  ges.  Schiess-u.  Sprengstoffwesen,  4,  175. 

Causes  and  Methods  of  Determining  Decomposition  of  Nitrocellulose.  Z. 
ges.  Schiess-u.  Sprengstoffwesen,  1,  395. 

Lunge  &  Beibie. — Contributions  to  the  Knowledge  of  Nitrocellulose.  Z. 
Angew.  Chem.,  14,  543,  561. 

Mittasch. — Stability  of  Nitrocellulose.     Z.  Angew.  Chem.,  16,  16,  929. 

Obermiiller. — Mitteil.  aus  dem  Berliner  Bezirks-verein,  etc.,  Oct.,  1904. 
See  Wilcox,  J.  Am.  Chem.  Soc.,  80,  271. 

Patterson. — Stability  Tests  of  Smokeless  Powder.  7th  International  Cong. 
Applied  Chem.  Explosives,  p.  99. 

Pleus. — Some  Improvements  in  the  Apparatus  for  the  Obermiiller 
Manometer  Test.  Z.  ges.  Schiess-und  Sprengstoffwesen,  5,  121. 

Robertson. — On  the  Will  Test  for  Nitrocellulose,  J.  Soc.  Chem.  Ind.,  21,  819. 

Rubin. — Testing  Regulations  and  Black  Powder  Safety  Explosive  in 
England.  Z.  ges.  Schiess-u.  Sprengstoffwesen,  4,  21. 

Saposhnikov. — Rate  of  Decomposition  of  Nitrocellulose  and  Temperature. 
Russ.  Phys.  Chem.  Soc.,  38,  1186. 

Snelling  &  Storm. — Behavior  of  Nitroglycerine  when  Heated.  Bureau  of 
Mines,  Technical  Paper  12,  1912. 

Sy. — Stability  of  Nitrocelulose,  J.  Am.  Chem.  Soc.,  25,  549;  Z.  Angew. 
Chem.,  18,  1824. 

Wilcox. — Decomposition  Curves  of  Nitrocellulose.  J.  Am.  Chem.  Soc.,  SO, 
271. 

Will.— Stability  of  NitroceUulose.  J.  Soc.  Chem.  Ind.,  20,  602;  Stability  of 
CeUuloid.  Z.  Angew.  Chem.,  19,  1386. 

Zschokke. — Testing  of  Explosives.  Z.  ges.  Schiess-u.  Sprengstoffwesen, 
6,  241. 


(Published  by  permission  of  the  Navy  Department) 


A     NEW    STABILITY    TEST    FOR    NITROCELLULOSE 

POWDERS 

BY  S.  A.  WEIRMAN 
U.  S.  Navy  Ordnance  Laboratory,  Olongapo,  P.  I. 

The  various  stability  tests  for  nitrocellulose  powders  in  general 
use  at  the  present  time,  depend,  with  various  differences  of  details, 
upon  one  process:  the  subjection  of  the  powder  to  temperatures 
sufficiently  high  to  decompose  the  powder  within  a  reasonable 
period  of  time,  and  from  the  result  thus  obtained  to  pass  judg- 
ment upon  the  keeping  qualities  of  the  powder  at  the  lower  tem- 
perature of  actual  storage  and  use,  i.  e.  the  "working  temperature" 
of  the  powder. 

While  experience  has  proven  the  value  of  these  tests  as  criteria 
of  the  actual  stability  and  possible  life  of  powder,  yet  so  many 
other  and  complicated  factors  enter  into  the  problem  that  it  is 
by  no  means  possible  to  consider  increased  temperature  as  the 
sole  cause  of  lowered  stability  and  therefore  apply  a  mathematical 
proportion  between  the  duration  of  test  of  a  powder,  even  at  a 
temperature  but  slightly  higher  than  the  working  temperature, 
and  the  life  of  a  powder  at  the  working  temperature.  Obviously, 
the  closer  the  test  approaches  the  working  temperature  of  the 
powder,  the  more  accurate  will  be  the  test,  but,  for  the  same 
reason,  the  time  consumed  in  concluding  the  test  increases  so 
rapidly  as  to  soon  place  a  limit  on  the  minimum  temperature 
which  can  be  used  to  complete  a  test  within  a  reasonable  period. 

In  the  opposite  direction  it  is  evident  that  a  test  at  any  tem- 
perature sufficiently  high  to  volatilize  or  decompose  any  of  the 
constituents  of  the  powder  cannot  be  compared  with  any  great 
degree  of  accuracy  to  the  resistance  of  the  powder  at  a  working 
temperature  where  such  decomposition  will  not  occur.  In  one 
instance  there  is  a  rapid  decomposition  caused  by  the  breaking 
down  of  a  constituent  of  the  powder  and  the  accompanying 
acceleration  of  decomposition  caused  thereby,  while  in  the  other 

157 


158  Original  Communications:  Eighth  International        [VOL. 

instance  there  is  but  the  slow  gradual  decomposition  of  the  powder 
in  its  entirety. 

It  must  be  acknowledged  that  all  heat  tests  approach  the 
problem  of  stability  from  but  one  direction;  that  of  decomposition 
by  heat.  The  65.5°C.  Surveillance  Test;  the  65.5°C.  and  80°C. 
Kl-Starch  Test;  the  110°C.  Vieille  Test;  the  115°C.  Ordnance  Test 
and  the  134.5°C.  German  Test  differ  in  the  main  only  by  difference 
in  temperature  employed. 

With  these  things  in  mind  and  realizing  the  value  of  a  corrob- 
oratory test  approaching  the  problem  of  stability  from  a  different 
direction  than  that  of  decomposition  by  heat,  the  attention  of 
the  writer  was  directed  to  the  question  of  moisture  effect  on 
nitrocellulose  powders  during  some  years'  experience  with  these 
powders  in  the  warm,  moisture-laden  climate  of  the  tropics, 
where  the  pronounced  effect  which  moisture  had  upon  the  keeping 
qualities  of  powder  and  the  tests  of  the  same  was  very  evident. 
Various  experiments  and  experience  with  powder  stored  in  warm, 
damp  magazines  both  ashore  and  aboard  ship  proved  conclusively 
that  while  moisture  in  powder  is  most  deleterious,  yet  the  presence 
of  the  moisture  may  be  regarded  as  an  effect  and  proof  of  low 
stability  rather  than  a  cause,  and  therefore  the  amount  of  moisture 
present,  or  rather  the  ability  of  the  powder  to  take  up  and  retain 
moisture,  serves  as  a  fair  criterion  of  the  keeping  qualities  of  the 
powder. 

This  may  be  explained  as  follows:  A  newly  made  nitrocellulose 
powder  consists  of  nitrocellulose  of  certain  limits  of  nitration 
dissolved  into  a  plastic  mass  by  a  solvent,  generally  of  ether- 
alcohol.  After  the  pressing  and  drying  processes  there  remains  a 
hard  colloid  containing  a  slight  amount  of  residual  alcohol  from 
the  ether-alcohol  solvent,  the  amount  depending  principally 
upon  the  size  and  shape  of  the  powder  grains.  Of  moisture  there 
is  but  the  very  small  amount  originally  in  the  solvent  and  remain- 
ing with  the  residual  alcohol  incorporated  with  the  powder  grain 
in  addition  to  the  surface  moisture  deposited  on  the  powder 
during  the  process  of  packing. 

In  the  course  of  years  of  storage  and  use  with  more  or  less 
exposure  to  changes  of  temperature  and  humidity,  the  residual 
solvent  slowly  evaporates  and  is  replaced  by  a  deposit  of  moisture. 


rv]  Congress  of  Applied  Chemistry  159 

This  moisture  probably  produces  a  hydrolytic  decomposition  and 
serves  to  accelerate  the  progress  of  decomposition  within  the 
powder  grain.  As  the  organic  ingredients  of  the  powder  gradually 
break  down  additional  H2O  is  formed,  an  accurate  measure  of 
which  might  serve  as  a  true  index  of  the  actual  condition  of  the 
powder.  But  at  any  time  the  amount  of  moisture  present  in  a 
powder  is  a  certain  criterion  of  its  stability  as  showing  the  porosity 
and  vulnerability  of  the  powder  grain,  and  while  density,  residual 
solvent  and  size  and  shape  of  grain  may  all  have  their  influence 
on  the  moisture  content,  yet  for  the  purpose  of  a  stability  test 
these  factors  may  be  disregarded.  The  following  test  may  then 
be  developed  as  correctly  indicating  the  stability  of  a  powder 
independent  of  any  heat  test  and  approaching  the  problem  from 
an  entirely  different  direction. 

A  suitable  powder  sample,  ten  grams  are  sufficient,  is  placed  in 
a  weighing-bottle  and  weighed.  Then  placed  in  a  sulphuric  or 
vacuum  desiccator  for  a  suitable  period.  Seven  days  have  been 
found  to  be  fully  sufficient  for  complete  drying.  Sample  then 
weighed  and  loss  of  weight  obtained.  Expose  sample  in  saturated 
atmosphere,  preferably  each  test  at  the  same  temperature,  until 
equilibrium  is  established.  Forty-eight  hours  in  a  Hempel  des- 
iccator containing  water  has  been  found  sufficient.  Obtain  gain 
in  weight.  Loss  in  weight  plus  gain  in  weight,  expressed  in  per 
cent  of  weight  after  desiccation  equals  moisture  range.  This 
range  corrected  for  surface  area  moisture  converts  all  size  powder 
grains  to  same  standard  for  comparison.  This  does  not  necessitate 
a  measurement  of  the  powder  grains  each  time  as  the  original 
dimensions  of  the  grain  when  manufactured  will  serve.  The 
observed  moisture  range  "r"  divided  by  surface  area  "a"  equals 

actual  moisture  range  "R".    —  =  R.    This  result  will  be  found  to 

a 

parallel  the  results  obtained  from  the  Kl-Starch  Test  and  help 
to  explain  the  sudden  unaccountable  drop  in  test  experienced 
with  some  powders  in  the  65.5°C.  Surveillance  Test  after  exposure 
to  unfavorable  hygrometric  conditions. 


ORIGINAL   COMMUNICATIONS 

EIGHTH   INTERNATIONAL 

CONGRESS 
OF  APPLIED  CHEMISTRY 


Washington  and  New  York 
September  4  to  13,  1912 

SECTION  IIIc:  SILICATE  INDUSTRIES 


VOL.  V 


ORIGINAL   COMMUNICATIONS 

EIGHTH   INTERNATIONAL 

CONGRESS 
OF  APPLIED  CHEMISTRY 


Washington  and  New  York 
September  4  to  13,  1912 

SECTION  IIIc:      SILICATE  INDUSTRIES 


VOL.   V 


The  matter  contained  in  this  volume  is  printed  in  exact  accordance  with  the  manuscript 
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alle  regole  que  governano  i  document!  e  le  publicazioni. 


THE     RUMFORD     PRESS 
CONCORD«N-H«U'S«A» 


ORIGINAL   COMMUNICATIONS 

TO  THE 

EIGHTH  INTERNATIONAL  CONGRESS 

OF 

APPLIED    CHEMISTRY 


APPROVED 

BY  THE 

COMMITTEE  ON  PAPERS  AND  PUBLICATIONS 

IRVING  W.  FAY,  CHAIRMAN 

T.  LYNTON  BRIGGS  JOHN  C.  OLSEN 

F.  W.  FRERICHS  JOSEPH  W.  RICHARDS 

A.  C.  LANGMUIR  E.  F.  ROBBER 

A.  F.  SEEKER 


SECTION  IIIc.     SILICATE  INDUSTRIES. 

EXECUTIVE  COMMITTEE. 

President:  ALLERTON  S.  CUSHMAN,  PH.D. 
Vice- President:  KARL  LANGENBBCK 
Secretary:  ZOLTAN  DE  HORTATH 
EDWARD  ORTON,  JR.,  E.M. 
HEINRICH  RIBS,  PH.D. 

SECTIONAL  COMMITTEE. 

L.  E.  BARRINGER,  E.M.  S.  V.  PEPPBL 

CHAS.  F.  BINNS,  M.S.  R.  C.  PURDY 

A.  V.  BLEININGER,  B.S.  CLIFFORD  RICHARDSON,  F.C.S 

S.  G.  BURT,  A.B.  KENNETH  SEAVER,  S.B. 

ELLIS  LOVEJOY,  E.M.  ALEXANDER  SILVERMAN,  M.S. 

RICHARD  K.  MEADE,  M.S.  F.  W.  WALKER 

S.  B.  NEWBERRY,  Pn.D.  ARTHUR  S.  WATTS 

L.  W.  PAGE  H.  A.  WHEELER,  E.M. 

and  the  Sectional  Executive  Committee. 


VOLUME  V. 

SECTION  IIIc:  SILICATE  INDUSTRIES. 
CONTENTS. 

BINNS,  CHARLES  F.  AND  MAKELEY,  C.  H. 

The  Coloring  Power  of  Iron  Compounds  in  Burned  Clay  7 

BLEININGER,  A.  V. 

The  Effect  of  Electrolytes  upon  Clay  in  the  Plastic  State  17 

COGGESHALL,    GEORGE   W.    AND   CtJSHMAN,    ALLERTON   S. 

The  Production  of  Available  Potash  from  the  Natural  Silicates  . .       33 
CUSHMAN,  ALLERTON  S.  AND  COGGESHALL,  GEORGE  W. 

The  Production  of  Available  Potash  from  the  Natural  Silicates  . .       33 
CUSHMAN,  ALLERTON  S. 

Notes  on  a  Study  of  the  Temperature  Gradients  of  Setting  Portland 

Cement  51 

FRZNK,  ROBERT  L. 

Causes  of  Breakage  in  Glass  Manufacture  and  Method  of  Differ- 
entiating Chemico-Heterogeneic  Strains  from  Cooling  Strains  ....       57 
HADLEY,  HARRY  F.  AND  MCFARLAND,  DAVID  F. 

The  Use  of  the  Higher  Phenols  in  Testing  for  Free  Lime  in  Port- 
land Cement  83 

KLEIN,  A.  A.  AND  PHILLIPS,  A.  J. 

Magnesia  in  Portland  Cement 73 

MAKELEY,  C.  H.  AND  BINNS,  CHARLES  F. 

The  Coloring  Power  of  Iron  Compounds  in  Burned  Clay 7 

MCFARLAND,  DAVID  F.  AND  HADLEY,  HARRY  F. 

The  Use  of  the  Higher  Phenols  in  Testing  for  Free  Lime  in  Port- 
land Cement 83 

PHILLIPS,  A.  J.  AND  KLEIN,  A.  A. 

Magnesia  in  Portland  Cement 73 

REIBLING,  W.  C.  AND  REYES,  F.  D. 

The  Physical  and  Chemical  Properties  of  Portland  Cement  91 

REYES,  F.  D.  AND  REIBLING,  W.  C. 

The  Physical  and  Chemical  Properties  of  Portland  Cement 91 

SCHMIDT,  WALTER  A. 

The  Control  of  Dust  in  Portland  Cement  Manufacture  by  the  Cot- 
trell  Electrical  Precipitation  Processes  117 


6  Contents  [VOL. 

SILVERMAN,  ALEXANDER 

Glass  Formulas — A  Criticism  125 

STALET,  HOMER  F. 

The  Viscosity  ofBorate  Glasses  127 


THE   COLORING   POWER   OF   IRON   COMPOUNDS   IN 
BURNED  CLAY 

CHARLES  F.  BINNS  AND  C.  H.  MAKELEY 

Alfred,   N.   Y. 

The  phenomena  which  attend  the  production  of  color  in  un- 
glazed  clay  wares  have  attracted  the  attention  of  many  investi- 
gators. It  has  been  shown  that  iron  is  the  most  prolific  colorant 
and  that  a  great  variety  of  hues  are  produced  by  it.  These  hues 
are  influenced  by  the  amount  of  iron  present,  by  the  form  in 
which  the  iron  occurs,  by  other  ingredients  in  the  clay  and  by 
the  nature  and  temperature  of  the  burning. 

The  subject  was  first  investigated  by  Hermann  A.  Seger  whose 
collected  works  have  been  translated  by  the  American  Ceramic 
Society.  He  says1  "  It  is  known  that  the  color  goes  through  all 
the  variations  from  white  through  yellow,  orange,  red,  blue, 
brown  up  to  black;  all  these  colors  are  produced  by  the  combi- 
nations of  iron  ";  and  again,2  "  It  is  known  that  the  oxide  of  iron, 
which  in  the  majority  of  cases  must  be  considered  the  only  color- 
ing constituent,  may  produce  a  great  variety  of  shades  from 
yellowish  red  to  violet  black,  according  to  its  state  of  division, 
and  it  will  always  assume  a  darker  color  when  the  clay  is  exposed 
to  a  high  temperature." 

The  normal  burning  of  a  red  clay  takes  place  under  oxydizing 
conditions,  hence  the  iron  will  always  ultimately  become  ferric 
oxide  unless  it  is  partly  combined  as  a  silicate.  Nevertheless  the 
original  source  of  the  iron  seems  to  be  of  profound  significance  in 
its  influence  upon  color.  Prof.  Orton  says  "  The  ferruginous 
minerals  which  are  most  commonly  found  in  clays  are: 

(a)  Ferric  oxide,  anhydrous  or  in  various  stages  of  hydration. 

(b)  Ferrous  carbonate. 

(c)  Ferric  sulphide  or  Pyrite. 

Collected  Writings,  Vol.  I,  p.  343. 
'Ibid,  p.  349. 


8  Original  Communications:  Eighth  International       [VOL. 

(d)  Ferrous  silicate  minerals,  like  Biotite,  Hornblend,  and 
many  others. 

(e)  Ferric   sand   minerals,    like   Magnetite,    Menaccanite, 
Chromite,  etc. 

It  is  from  the  first  three  minerals1  that  we  derive  the  principal 
beneficial  or  detrimental  effects  of  iron." 

And  again,  "  The  effect  of  these  various  minerals  on  the  color 
of  clays  is  not  in  itself  strongly  marked  or  characteristic.  That  is, 
as  good  a  red  color  may  be  developed  from  a  clay  containing  its 
iron  as  ferrous  carbonate  as  from  ferric  hydroxide."  "  Ferric 
sulphide2  is  invariably  found  in  granular  form.  These  gran- 
ules may  be  large  or  small  but  they  are  never  small  enough  to 
give  a  red  color." 

Certain  opinions  have  been  advanced  also  by  the  above  quoted 
writers  upon  the  influence  of  the  other  ingredients  of  the  clay 
upon  the  color  of  the  iron.  It  is  admitted  on  all  sides  that  lime 
exerts  a  powerful  effect  in  producing  a  buff  color  in  a  clay  which 
otherwise  would  burn  red.  Magnesia  has  a  similar  influence  but 
somewhat  less  marked.  The  substance  upon  which  there  is  a 
difference  of  opinion  is  alumina.  Seger  says,  "If  we  wish  to 
classify  the  clays  according  to  the  colors  which  the  mass  assumes 
on  burning3  we  can  divide  them  into  four  groups: — 

1.  Clays  high  in  alumina  and  low  in  iron.    These  burn  white 
or  to  a  scarcely  noticeable  color. 

2.  Clays  high  in  alumina  containing  moderate  amounts  of  iron ; 
their  color  ranges  from  pale  yellow  to  buff. 

3.  Clays  low  in  alumina  and  high  in  iron,  the  brick  clays,  burn- 
ing red. 

4.  Clays  low  in  alumina,  high  in  iron  and  lime,  the  brick  clays 
burning  yellow,  or  clay  marl/' 

Prof.  Orton  (p.  389)  "  cannot  give  unconditional  assent.  The 
evidence  Seger  marshalls  is  strong  and  undoubtedly  points  to  his 
conclusion.  But  if  it  were  true,  then  synthetic  mixtures  should 

1U  On  the  Role  played  by  Iron  in  the  Burning  of  Clays."    Transactions  of 
the  American  Ceramic  Society,  Vol.  V,  p.  384. 
2Ibid,  p.  387. 
'Collected  Writings,  p.  109. 


v]  Congress  of  Applied  Chemistry  9 

easily  give  the  buff  color,  which  has  not  been  the  writer's  ex- 
perience. We  certainly  find  an  amazing  uniformity  in  the  color 
of  buff  burning  clays,  while  their  iron-alumina  ratios  fluctuate 
very  greatly.  Some  fire  clays  contain  40  per  cent,  of  alumina  and 
0.5  per  cent,  of  iron,  and  burn  to  a  good  buff.  Others  contain  15 
or  20  per  cent,  of  alumina  and  2.5  to  4  per  cent,  of  iron  and  burn 
to  almost  exactly  the  same  tint.  Other  clays  of  different  geolog- 
ical history,  containing  about  the  same  alumina  and  iron  burn  to  a 
fine  red  color." 

The  present  investigation  was  undertaken  with  the  view  of 
throwing  some  light  upon  the  case  and  is  an  attempt  to  ascertain 
the  effect  of  the  most  common  sources  of  iron  under  the  influence 
of  silica  and  alumina  respectively.  The  influence  of  temperature 
was  also  considered  so  that  the  tests  were  prepared  in  duplicate, 
one  series  being  burned  at  1200  degrees  C.  and  the 
other  at  1270  degrees  C.  These  are  high  temperatures 
for  red  burning  clays  but  the  mixtures  made  were  very 
much  more  refractory  than  would  be  the  case  with  natural  clays. 
The  foundation  of  the  mixtures  is  an  English  plastic  ball  clay 
which,  together  with  the  iron,  forms  40  per  cent,  of  the  mass. 
The  remaining  60  per  cent,  is  ground  quartz  in  the  first  member 
and  pure  alumina  in  the  last.  The  intermediate  members  contain 
40  and  20  per  cent,  of  the  quartz  and  20  and  40  per  cent,  of  the 
alumina  respectively;  the  iron  content,  calculated  as  ferric 
oxide,  is  2.5  per  cent,  in  the  first  line,  5  per  cent,  in  the  second, 
and  10  per  cent,  in  the  third,  these  amounts  being  subtracted 
from  the  ball  clay  so  that  the  iron  content  is  constant  in  a  hori- 
zontal direction  and  the  other  ingredients  are  constant  in  a  ver- 
tical direction. 

The  first  series  was  made  up  with  commercial  ferric  oxide,  the 
whole  mixture  being  ground  together  in  water  in  a  porcelain  ball 
mill.  An  inspection  of  the  results  shows  that  no  red  color  can  be 
expected  from  this  source.  The  prevailing  tone  is  a  pinkish  gray, 
the  color  being  somewhat  lightened  as  the  content  of  alumina 
increases.  At  the  lower  fire  the  alumina  produces  no  change  in 
hue  but  simply  a  lighter  tint.  This  is  probably  due  to  the  fact 
that  the  alumina  is  more  bulky  than  the  quartz  and,  consequent- 
ly, the  whitening  effect  is  greater.  At  the  greater  heat,  however, 


10  Original  Communications:  Eighth  International        [VOL. 

the  tone  of  the  color  is  changed,  as  the  alumina  increases,  to  buffs 
of  varying  strength.  This  is  especially  the  case  at  the  5  per  cent, 
iron  content,  though  it  is  apparent  in  every  instance. 

In  the  second  series  the  iron  was  introduced  as  a  precipitate, 
thus  stimulating  the  effect  of  limonite.  A  solution  of  ferrous 
sulphate  was  prepared  and  the  volume  necessary  to  contain  the 
proper  amount  of  iron  was  added  to  the  clay  mixture  after  grind- 
ing. Sufficient  ammonia  to  precipitate  the  hydroxide  was  then 
mixed  with  the  fluid  which  was  then  washed  free  from  ammonium 
sulphate.  It  was  not  found  necessary  to  oxydize  the  solution  in 
advance  as  the  clay  speedily  changed  from  green  to  orange  from 
atmospheric  influence.  The  results  are  interesting.  At  the  lower 
fire  a  number  of  reds  appear.  The  alumina  shows  the  lightening 
effect  already  mentioned  but  no  actual  change  of  hue.  At  the 
higher  temperature,  however,  there  are  some  marked  changes 
especially  in  the  5  per  cent.  iron.  Here  are  two  excellent  buff 
colors  showing  that  alumina  has  a  marked  effect  when  the  heat 
is  sufficient  to  cause  it  t«  react.  It  appears  that  alumina  is 
powerless  to  overcome  the  red  tones  when  the  iron  stands  as  high 
as  10  per  cent. 

The  third  series  contains  the  iron  in  the  form  of  siderite,  FeCOs. 
A  supply  of  the  mineral  was  obtained  and  the  iron  content  ascer- 
tained. The  proper  quantity  was  then  ground  with  the  clay. 
At  the  low  fire  the  mineral  has  no  tendency  to  produce  a  red  or 
even  a  brown  color.  Nothing  appears  but  various  shades  of  gray. 
At  the  higher  temperature  the  prevailing  color  is  brown,  in- 
fluenced towards  gray  on  the  increase  of  alumina  content. 

In  the  fourth  and  last  series  pyrite  was  the  source  of  the  iron. 
The  procedure  was  the  same  as  in  the  third  series.  Some  interest- 
ing developments  have  arisen  from  the  fact  that  the  pyrite  has 
oxydized  in  part  as  the  clay  samples  were  slowly  dried.  In  this 
the  result  may  be  regarded  as  a  combination  of  series  1  and  series 
2.  Where  the  clay  has  dried  rapidly  as  on  the  edges  the  iron 
appears  as  the  anhydrous  oxide  but  where  a  previous  oxidation 
has  taken  place  the  effect  appears  as  though  the  hydrous  oxide 
had  been  formed.  At  the  higher  temperature  there  is  an  inter- 
esting array  of  buff  colors,  especially  at  the  5  per  cent,  iron 
content. 


y]  Congress  of  Applied  Chemistry  11 

There  are  certain  points  which  appear  evident  from  these 
experiments. 

1.  It  is  not  possible  to  produce  red  colors  in  burned  clay  by  the 
use  of  pulverized  iron  bearing  minerals,  however  finely  they  may 
be  ground,  but  buff  tones  are  produced  under  the  influence  of 
alumina  and  at  a  temperature  at  which  the  clay  approaches 
vitrification.    These  buff  colors  are  apparently  due  to  the  blend- 
ing of  a  multitude  of  minute  brown  specks. 

2.  Red  colors  are  the  result  of  a  precipitation  of  a  colloidal 
iron  compound  in  the  clay  mass.    This  precipitation  apparently 
results  from  a  solution  of  ferrous  sulphate,  which  is  itself  the 
result  of  the  oxidation  of  pyrite,  either  becoming  oxydized  with 
the  separation  of  limonite  or  meeting  with  carbon  dioxide  in  some 
form  with  the  resulting  precipitation  of  ferrous  carbonate.    This 
is  the  only  way  of  explaining  the  statement  of  Prof.  Orton,  quoted 
above,  that  "  as  good  a  red  color  may  be  developed  from  a  clay 
containing  its  iron  as  ferrous  carbonate  as  from  ferric  hydroxide." 
Siderite  does  not  decompose  under  ordinary  conditions  and  in  the 
finely  ground  form  no  red  is  produced. 

3.  Pyrite  is  responsible  for  several  phenomena.     As  already 
stated  it  is  the  parent  of  other  forms  of  iron  and  while  it  is  true 
as  stated  by  Orton  that  the  granules  of  pyrite  "  are  never  small 
enough  to  produce  a  red  color  ,"  it  is  also  true  that  pyrite  is 
extremely  susceptible  of  oxidation.    Unless  the  clay  containing 
this  mineral  is  dried  very  rapidly  ferrous  sulphate  and  ultimately 
ferric  hydroxide  will  be  found.    There  are  examples  of  this  in  the 
specimens  shown;  in  fact,  in  these  there  is  the  actual  birth  of  a 
red  clay. 

4.  Alumina  is  undoubtedly  responsible  for  the  production  of 
buff  colors  and  in  this  the  opinion  of  Seger  is  confirmed.    At  the 
same  time  it  must  be  admitted  that  the  effect  of  alumina,  added, 
as  in  these  experiments,  in  the  pure  form,  may  be  different  from 
that  of  combined  alumina.     Possibly  the  different  behavior  of 
clays  with  a  similar  content  of  alumina  and  iron  may  be  ac- 
counted for  in  this  way. 


I. 


Fe,( 
5.< 


FPaO. 

10!$ 


PLATB   FT 


Pe,< 

?.' 


10. 


FERRIC     OXIDE 
Cone  3  1200*  C. 


Si08  60         Si02  40          SiOa  20          SiO,  — 
Ai^O.  —         Al»0,  20          AlaO,  40          Al,0,  -60 

Gray 

Gray 

Light  Gray 

Light  Gray 

Pinlcleh  Gray 

Gray 

Light  Gray- 

Light  Gray 

tight  Pink 
Chocolate 

pinkish  Gray 

Gray 

Light  Gray 

FERRIC        OXIDK 
Cone  5  IS^ 


S102  50          Si02  40           Si08  20           SIO,  — 
A1203  —         AlaOa  ?0          Al20a  40          Al,0,  50 

arayleh  Buff 

Buff 

Light  Bftff 

Cream 

Dark  Pinkish 
Gray 

Dark  Buff 

Light  Buff 

Cream 

Pink  Chocolate 

Brown 

Grayish  Buff 

Dark  Buff 

PLATS  III. 


10. ( 


PLATS  TV 


10. 0# 


B  R  R  I  C       HYDROXIDE 
Cone  3.       '  1200*  C. 


S10,  60         Si02  40         810,  20          810t  — 
Al,0a  —         A180,  20         A180,  40          Al«0,  60 

Pinkish  Red 

Light  Red 

Pinkish  Buff 

Light  Pink 
Buff 

Bright  Bed 

Bright  Red 

Pale  Red 

Light  Pink 

Strong  Red 
I 

Bright  Red 

Bright  Red 

Pale  Bed 

B  R  R    T   C       HYDBOXTDB 
Cone  6.  12?0"C. 


SiO,    60-                      S10,    40                       810,    20                         Sl08    •- 
Al,08    —                      Al,03    20                      Al,0,    40                        Ala09    50 

Pinkish  Red 

Strong  Buff 

Buff 

Light   Buff 

Medium  Bed 

Light  Red 

Strong  Buff 

Buff 

Dejrk  Red 

lledlun  Red 

Red 

Red 

PLA22S..V. 


BIO,    60 
Ai80,  - 


SIDBRITB 
Cone  3.  1200" C. 


S108  40 
Ala08    20 


SiOa   20 
40 


A1808    60 


Cray 

Gray 

Medium  Gray 

Light  Gray 

Dark  Gray 

Dark  Gray 

Gray 

Gray 

Strong  Gray 

Dark  Gray 

Dark  Gray 

Gray 

Pea< 
2.', 


Pe20j 


io!o;l 


SlOa  6Q 
A1403  -•* 


SIDBRITB 
Cone  6.  1270*0. 


Si02   40 
Al,0,   20 


20 
A1203    40 


SiO*  — 

A1303    60 


STOWQ 

Brown  Buff 

Light  Brown 

Light  Brown 

Dark  Brown 

Brown 

Brown 

Gray 

i 
Black 

Dark  Brown 

Brown 

Dark  Gray 

PL&EX  VIZ. 


810, 

41,0, 


Gray 


Fed 


Pinkish  Gray 


Purple 


Dark  Brown 


PLATE  VIII. 


.a. 
10.0% 


t^t  R  t  t  Z 

Co  no.  3.     1200*  C. 


40 

20 


810,  30 
AlaOs  40 


Pinkish  Gray 


Purple 


Perk  Red 


Orar 


Gray 


Red 


Gray 


Red   \ 


>  ^  B  I  T  E 
Cone  6.    1270* C 


SiO-  — 
60 


Gray 


Gray 


Bed 


Gray 


Red 


SiOa  60         Si02  40          Si02  30         6J03  — 
AlnO^  —          Al.O.  20           A1^O_  4O          A1_O-  fin 

Dark  Buff 

Buff 

Buff 

Light  Buff 

Purpla  Brown 

BuTf 

Buff 

Buff 

Dark  Brown  Red 

Purple  Brown 

Purple  Brown 

Purple  Brown 

THE  EFFECT  OF  ELECTROLYTES  UPON  CLAY  IN  THE 
PLASTIC  STATE 

BY  A.  V.  BLEININGER 
Ceramics  Department,    University  of  Illinois,    Urbana,   Illinois 

It  is  a  well  known  fact  that  clays,  suspended  in  water,  are 
affected  in  a  most  decided  manner  by  the  presence  of  electrolytes. 
This  susceptibility  of  clay  slips  is  illustrated  in  a  striking  manner 
by  the  use  of  sodium  carbonate  and  sodium  silicate  in  the  casting 
process  where  small  amounts  of  these  reagents  bring  about  a 
considerable  reduction  in  the  amount  of  water  required  to  cause 
fluidity  and  consequently  in  the  drying  shrinkage.  According  to 
the  opinion  of  many  writers,  this  and  similar  phenomena  are  con- 
nected with  the  colloidal  nature  of  certain  constituents  of  clays. 
Thus  Schloesing1  separated  from  kaolin,  1.47  per  cent,  of  a  volum- 
inous material  which  he  called  colloidal.  Van  Bemmelen,2 
Rohland,3  Cushman,4  Ashley5  and  others  ascribe  such  properties 
as  the  plasticity  of  clays,  the  cementing  power  of  ground  rock,  etc., 
to  the  content  of  colloid  matter. 

That  clays  contain  material  of  a  colloid  character  seems  to 
have  been  proven  conclusively.  The  amounts  of  such  substance, 
however,  are  not  as  great  as  has  been  supposed  and  the  general 
properties  of  the  clays  are  governed  to  a  very  considerable  extent 
by  the  large  quantities  of  granular  matter  usually  present.  The 
latter  occurs  in  all  sizes  from  coarse  grains  down  to  particles  so 
small  that  they  show  Brownian  movement.  It  is  obvious  that 
only  the  finest  material  remaining  in  suspension  is  affected  by  the 

JThe  Constitution  of  Clays:  Compt.  Rend.,  Vol.  79,  1874,  pp.  376-380, 
473-477. 

2Chem.  Zentralblatt  (1882)  p.  1255;  z.f.anorg.  Chem.  18,  p.  14  (1898);  23, 
p.  321  (1900). 

3Zeitschrift  f.  anorg.  Chem.,  1902,  158;  1904,  325. 

4J.  Am.  Chem.  Soc.  1903,  451;  Trans.  Am.  Ceram.  Soc.  6,  65. 

'Bull.  388,  U.  S.  Geol.  Survey. 

2  17 


18  Original  Communications:  Eighth  International        [VOL. 

presence  of  electrolytes  and  other  conditions.  As  is  well  known, 
the  behavior  of  suspended  particles  is  governed  by  the  slight  quan- 
tities of  electrolytes  present  in  solution.  The  direction  in  which 
suspension  colloids  travel  under  the  influence  of  an  electric  cur- 
rent is  determined  principally  by  the  small  amount  of  dissolved 
substance  and  is  not  so  much  a  function  of  the  kind  of  colloid 
itself.  Thus  a  slight  increase  in  the  hydrogen  ions  in  water  impart 
to  a  hydrosol  a  positive  charge  so  that  its  particles  move  towards 
the  negative  pole.  On  the  other  hand,  an  addition  of  hydroxyl 
ions  brings  about  a  negative  charge  causing  the  particles  to  move 
towards  the  positive  pole.  The  migration  velocity  of  all  hydrosols 
is  practically  the  same  and  according  to  Whitney  and  Blake,  they 
possess  about  the  same  velocity  as  the  mono  valent  ion  of  an 
inorganic  salt.  The  addition  of  ions  possessing  a  charge  opposite 
to  that  of  the  colloid  particles  causes  them  to  precipitate  or  to 
coagulate.  Hence  a  negatively  charged  colloid  is  coagulated  by 
a  positive  ion.  Ions  of  the  same  sign  either  do  not  effect  coagula- 
tion or  tend  to  keep  the  sol  in  its  original  condition.  The  coagulation 
capacity  of  an  ion  is  proportional  to  its  valency.  A  bi  valent  ion 
has  a  greater  coagulation  capacity  than  a  mono  valent  one  in  the 
ratio  of  y/2  0  =1:6  :1.  A  smaller  amount  of  electrolyte  is 
required  if  the  reagent  is  added  at  once  than  when  it  is  introduced 
in  smaller  portions.  Oppositely  charged  hydrosols  coagulate 
each  other.  The  flocculating  colloid  invariably  carries  part  of  the 
electrolyte  down  with  it  and  it  seems  to  prefer  the  ion  which  has 
the  same  charge. 

In  the  case  of  a  clay  suspension  we  may  then  assume  that  each 
particle  is  surrounded  by  an  adsorption  envelope  which  is  formed 
by  an  interchange  with  the  dispersion  medium. 

Flocculation  consists  in  the  consolidation  of  the  particles  after 
the  addition  of  the  electrolyte.  In  order  that  the  particles  may 
unite,  the  thin  envelope  of  liquid  must  be  broken.  This  does  not 
take  place  simultaneously  but  slowly.  As  soon  as  the  particles 
have  become  large  enough  for  the  Brownian  movement  to  cease, 
coagulation  becomes  more  rapid.  If  the  particles  are  uncharged 
they  adhere  most  readily  and  hence  the  soil  is  least  constant. 

A  kaolin  suspension  is  very  sensitive  to  impurities.  The 
charges  of  the  kaolin  particles  are  very  slight  and  according  to 


v]  Congress   of  Applied  Chemistry  19 

Bodlaender  negative  in  character.1  They  are  coagulated  by  di  and 
tri  valent  cations  more  strongly  than  by  mono  valent  ones. 
Bases  have  a  high  coagulating  value  referred  to  the  clay  particles 
while  non  electrolytes  do  not  precipitate.  Acids  coagulate  more 
strongly  than  di  valent  cations.  On  the  other  hand,  OH'ions 
possess  a  strongly  de-flocculating  character.2  Ashley  has  sum- 
marized the  principles  underlying  the  effect  of  various  electrolytes 
and  non  electrolytes  upon  clay  suspensions  quite  satisfactorily.3 

Giving  our  attention  to  some  of  the  practical  applications  of 
these  conceptions,  it  was  found  by  Simonis4  and  Boettcher5 
that  the  best  condition  of  a  slip  for  casting  is  that  corresponding 
to  maximum  deflocculation  which  at  the  same  time,  shows  mini- 
mum viscosity.  Ashley  was  inclined  to  think  that  a  point  just 
short  of  this  state  might  give  best  results. 

The  plastic  state  might  be  considered  as  a  special  case  of  clay 
in  suspension,  in  which  the  particles  approach  each  other  so 
closely  that  cohesive  forces  come  into  play.  During  the  process 
of  drying,  the  particles  approach  each  other  more  and  more  closely 
until  they  come  in  contact.  The  water  which  has  been  evaporated 
up  to  this  point  is  termed  shrinkage  water.  The  remaining  water 
content  filling  the  interstices  between  the  clay  particles  is  called 
pore  water.  This  term  includes  also  part  of  that  portion  which 
upon  heating  the  clay  to  110°  still  persists  in  adhering  to  the  mass 
and  which  is  expelled  only  at  still  higher  temperatures,  the  last 
traces  being  driven  off  only  at  red  heat,  and  known  as  hygroscopic 
moisture. 

It  has  been  realized  for  some  time  that  the  properties  of  the 
clays  are  influenced  by  the  presence  of  electrolytes.  Seger6 
explains  the  increase  in  the  plasticity  of  clay  upon  storing  by 
the  assumption  that  the  fermentation  of  organic  substances 
results  in  acids  which  neutralize  the  alkalinity  due  to  decomposed 


^ottinger  Nachrichten,  1893,  p.  267. 

2Freundlich,  Kapillar  Chemie,  chapter  on  suspension  colloids. 


3Trans.  Am.  Ceram.  Soc.  12,  p.  768. 
4Sprechsaal  1905,  No.  31. 
'Sprechsaal  1909,  Nos.  9-17. 
•Tonindustrie  Zeitimg  1891,  p.  813. 


20  Original  Communications:  Eighth  International        [VOL. 

feldspar,  and  in  addition  bring  about  the  desired  "  sour  "  condi- 
tion which  accompanies  the  improvement  in  the  working  qualities. 

Rohland1  discusses  this  subject  at  length  and  comes  to  the  con- 
clusion that  the  plasticity  of  clays  is  increased  by  the  presence  of 
H°  ions,  the  OH'  ions  on  the  other  hand  being  active  in  the 
opposite  sense.  Other  means  of  accomplishing  the  same  result 
consist  in  the  addition  of  colloids  like  tannin,  dextrine  etc.,  as 
has  been  shown  by  the  work  of  Acheson,  and  the  storing  of  the 
clay  in  cool  and  moist  places.  Coagulation  is  coincident  with 
increase  in  plasticity  and  is  primarily  due  to  the  presence  of 
hydrogen  ions;  it  is  retarded  by  the  hydroxyl  ions.  The  salts  of 
strong  bases  and  weak  acids  which  dissociate  OH'  ions  hydrolyt- 
ically  produce  an  effect  similar  to  that  of  the  hydroxyl  ions. 
Neutral  salts,  Rohland  goes  on  to  say,  with  but  few  exceptions, 
are  indifferent  in  their  effect  though  some  appear  to  show  a 
contradictory  behavior  which  has  not  been  explained.  "  The 
effect  of  the  hydroxyl  ions  may  be  weakened,  compensated  or 
strengthened  by  the  cation  of  the  salt  in  question.  Thus  borax 
is  an  example  of  the  first  class  and  Na2CO3  of  the  second." 

The  same  author  further  says  that  with  some  clays  the  addition 
of  Na2COs  brings  about  an  improvement  in  plasticity  while 
ordinarily  the  same  reagent  behaves  in  the  opposite  way  due  to 
the  hydrolytic  dissociation  of  OH'  ions.  It  is  possible  that  the 
effect  of  the  OH 'ions  might  be  compensated  by  the  presence  of 
the  CO3"  ions. 

The  perusal  of  literature  dealing  with  this  subject  shows  a 
decided  lack  of  determinations  resulting  in  numerical  values, 
in  fact,  practically  no  results  are  available  as  far  as  the  effect 
of  various  reagents  upon  clays  in  the  plastic  state  is  concerned. 
For  this  reason,  it  was  thought  desirable  to  begin  the  study  of 
certain  electrolytes  as  regards  their  action  upon  some  well  known 
plastic  clays  without  reference  to  theoretical  considerations.  The 
most  obvious  criterion  to  be  used  in  this  connection  is  the  shrink- 
age in  volume  which  clays  undergo  in  being  dried  under  constant 
conditions.  It  is  evident  that  any  effect  caused  by  the  addition 
of  reagents  to  clay  will  be  at  once  indicated  by  the  shrinkage. 


Tone,  pp.  35-49. 


v]  Congress   of  Applied  Chemistry  21 

From  what  we  know  of  the  practical  properties  of  clay,  we  are 
justified  in  assuming  that  shrinkage  is  a  function  of  plasticity. 
In  these  series  of  experiments,  two  clays  were  employed,  plastic 
Georgia  kaolin  and  Tennessee  ball  clay.  The  method  of  procedure 
consisted  in  preparing  a  thoroughly  mixed  sample  of  the  clay  in 
question,  weighing  out  sufficiently  large  portions  and  adding  the 
desired  amount  of  the  salt  in  solution.  After  preparing  a  thor- 
oughly worked  mass  of  the  desired  plastic  consistency,  it  was 
stored  in  a  moist  chamber  for  24  hours  in  order  to  make  reasonable 
allowance  for  any  time  effect.  The  lump  of  clay  was  then  molded 
in  a  brass  form  into  bars  10  x  2.5  x  0.625  cm,  which  were  at  once 
weighed.  The  volume  of  these  specimens  was  determined  in  a 
voluminometer  connected  to  a  burette  which  permitted  of  reading 
easily  to  0.05  cc.  The  measuring  liquid  used  was  petroleum  from 
which  the  lighter  constituents  had  been  driven  off  by  long  con- 
tinued heating.  For  each  concentration  of  salt,  three  bars  were 
made  and  measured.  The  specimens  were  then  allowed  to  dry 
at  the  laboratory  temperature  for  three  days  after  which  time 
they  were  heated  in  an  oven  regulated  by  a  thermostat  to  110°, 
to  constant  weight.  The  dry  bars  were  at  once  weighed  and 
immersed  in  petroleum  until  completely  saturated  when  they 
were  placed  in  the  voluminometer  for  the  determination  of  the  dry 
volumes. 

In  order  to  establish  the  limits  of  the  working  consistencies 
of  such  clays,  samples  of  three  clays  were  carefully  made  up  into 
bars  representing  the  extremes  of  the  plastic  state,  i.e.,  so  dry 
at  one  end  of  the  series  that  the  mass  could  barely  be  worked  and 
as  wet  at  the  other  end  as  the  clay  would  permit.  The  drying 
shrinkages  were  then  determined  as  usual.  The  curves  of  Fig.  1 
represent  the  results  of  this  work.  It  is  at  once  observed  that 
the  kaolins  possess  but  a  short  range  of  working  consistency,  as  is 
to  be  expected,  and  the  middle  point  of  each  curve  represents  the 
best  molding  condition.  In  fact,  for  clays  of  this  type  the  proper 
consistency  is  determined  by  the  "  feel  "  with  considerable  accm- 
racy.  In  the  case  of  the  ball  clay,  however,  the  range  is  far  more 
extensive  and  the  best  consistency  is  not  so  readily  made  evident 
by  the  working  of  the  plastic  mass.  But  here  likewise  the  middle 
point  of  the  curve  stands  for  the  most  satisfactory  molding  con- 
dition. The  far  greater  amount  of  water  required  by  the  ball 


22  Original  Communications:  Eighth  International       [VOL. 


clay  and  the  accompanying  large  shrinkage  as  compared  with  the 
kaolins  is  characteristic  of  this  type  of  material  and  differentiates 
it  sharply.  The  amount  of  water  required  by  each  clay  for  the 
best  working  consistency  was  thus  determined  and  maintained 


r 
*. 

i 

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And  Wati 

Curves 
Re/afto 
rCcmtef 

for   Thr 
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tfater  /s 

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7  To  Ma 
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3O  34  38  42  46  SO 

PERCENT  HATER  BY  WEIGHT 0#  DR Y  WEIGHT 
Figure  1. 

constant  in  most  of  the  subsequent  series  employing  solutions 
of  the  various  salts.  In  several  series  that  consistency  was  main- 
tained which  gave  the  best  working  condition,  a  procedure  which 
introduces  slight  variations. 

The  electrolytes  used  were  NaCl,  CaCl2,  A1C13,  Na2SO4   and 
BaCl2.  The  first  three  reagents  were  employed  for  the  purpose  of 


Congress  of  Applied  Chemistry 


23 


determining  the  effect,  if  any,  of  valency.  In  Fig.  2,  the  curves 
showing  the  effect  of  the  chlorides  of  sodium,  calcium  and  aluminum 
upon  the  shrinkage  of  Georgia  kaolin  are  given  and  it  is  noted  that 
both  the  CaCla  and  A1C13  are  more  effective  than  the  NaCl  in 


MS          W    A50    .0625     .075  JO 

GRAMS  ELECTROLYTE  PER  IOO  GRAMS  DRY  CLAY 
Figure  2. 

amounts  less  than  0.04  per  cent.  With  a  content  of  0.05  per  cent, 
the  sodium  salt  brings  about  the  same  decrease  in  shrinkage  as 
smaller  amounts  of  the  other  chlorides.  Based  on  molecular 
equivalents,  these  reagents  are  effective  in  the  order  of  the 
valency  of  the  respective  metals,  the  A1C13  being  most  active  and 
the  NaCl  least  in  decreasing  shrinkage.  The  interesting  fact  is 


24  Original  Communications:  Eighth  International        [VOL. 

brought  out  that  very  small  additions  of  any  of  these  reagents, 
maintaining  the  same  amount  of  liquid,  cause  a  marked  increase 
in  the  shrinkage  above  that  obtained  with  the  same  volume  of 
water.  In  each  case  however,  a  sudden  drop  takes  place  down  to 
approximately  the  same  shrinkage.  The  cause  of  the  dual  be- 
havior of  the  electrolytes  is  to  be  sought  in  dissociation  phe- 
nomena. It  was  found  that  the  clay  in  question  possessed  a  dis- 
tinct acid  reaction.  In  the  case  of  Aids,  for  instance  hydrolytic 
dissociation  would  tend  to  produce  additional  H'ions  and  conse- 
quently an  increase  in  plasticity  and  in  shrinkage.  According  to 
Rohland  such  chlorides  as  NaCl  and  CaC^  should  be  entirely 
neutral.  This  is  not  the  case  since  all  of  the  three  salts  in  greater 
concentrations  produced  a  measurable  decrease  in  shrinkage. 

The  use  of  NaCl  is  of  special  interest  in  this  connection  since 
experiments  carried  on  in  this  laboratory  showed  that  in  the  case 
of  exceedingly  plastic  clays  of  tertiary  origin  the  plasticity  was 
greatly  decreased  by  the  use  of  salts  solution  which  was  strikingly 
demonstrated  by  their  drying  behavior.  Brickettes  made  from 
the  untreated  clay  cracked  and  checked  very  badly  while  speci- 
mens made  up  with  a  NaCl  solution  dried  normally  without  the 
slightest  evidence  of  cracking  and  at  the  same  time  possessed  a 
greatly  reduced  drying  shrinkage. 

In  order  to  show  to  what  extent  the  relation  between  shrinkage 
and  pore  water  is  affected  by  the  use  of  these  reagents  the  total 
and  shrinkage  water  were  calculated  in  terms  of  the  true  clay 
volume.  For  this  purpose  the  density  of  the  powdered  clay  was 
determined  by  means  of  the  pycnometer  under  the  usual  precau- 
tions. The  volume  of  the  shrinkage  water  was  then  calculated 
from  the  evident  relation: 

100  (vi  —  v2)  =  per  cent,  shrinkage  water  (by  volume) 
w 


d 
where  Vi  =  volume  of  wet  brickette 

¥2  =  volume  of  dried  brickette 

w  =    weight  of  brickette  dried  at  110° 

d   =  density  of  clay. 

Similarly,  the  volume  of  the  total  water  referred  to  that  of  the 
clay  was  computed. 


v] 


Congress  of  Applied  Chemistry 


25 


In  Fig.  3,  this  relation  is  shown  graphically  for  the  addition  of 
NaCl.  It  is  seen  that  the  shrinkage  water  volume  was  first 
increased  and  then  slightly  decreased.  The  decrease  is  due  to  a 
drop|in  the  total  water  and  a  rise  in  the  pore  water  curves.  The 

A/ACL  WITH  GEORGIA  KAOLIN 


00 
^00 

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PERCENT  VOLUMES  IN  TEKM3  OF  TRL 

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Volume. 

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«o$-e'°.««$     *«5  040     .»50       ofczs      ^;S  JO 

GRAMS  N*Ct   t>£ft  IOO  GRAMS  DRY  CLAY 

Figure  3. 

effect  of  sodium  chloride  upon  Tennessee  ball  clay  is  shown  in  Fig. 
4,  where  again  the  shrinkage  is  first  increased  and  later  diminished 
by  greater  concentrations  of  the  salt.  In  Fig.  5,  the  volume  rela- 
tions are  again  indicated  and  it  is  observed  that  the  small  reduc- 
tion in  shrinkage  is  due  principally  to  the  decrease  in  the  amount 


26            Original  Communications:  Eighth  International        [VOL. 

PERCENT  VOL  <SHK1NKA&C  TERMS  Of  DRY  CLA  Y  VOLUME 
Sfcl*S*:»a 

MAC*  a 

r^e 

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P€RCLHT,H*Ct  IN  TERMS  OF  DRY  T£flH£d$££  BALL 
Figure  4. 


AY 
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A 


SHRINKAGE. 


POKE. 


WATE: 


100   GKAM3 

Figure  5. 


Congress   of  Applied  Chemistry 


27 


of  total  water.  The  relation  of  total  water  content  and  shrinkage 
water  established  for  the  clay  when  made  up  with  pure  water 
also  was  disturbed  by  the  use  of  the  reagents  as  is  seen  from  the 

AM,   WITH   G5ORG/A    KAOLIM 


PERCEMT  VOLUMES-  IN  TERMS  Of  TRUE  CLAY  VOLUME 
J&.Stf*  &£<??*$ 

/\ 

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Volume 

Tri 

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Volume 

Ltne 

9*oy"MMt     •tas          .0*0     Mo      +*U       aj6                    .to 

GKAMS  AJCt3  PER  JOO  GRAMS  DRY  CLAY 


Figure  6. 

dotted  pore  water  line  which  corresponds  to  the  shrinkage  which 
the  clay  should  show  when  made  up  with  the  given  volumes  of 
distilled  water. 

The  volume  relations  obtaining  for  the  A1CU  series  are  illus- 
trated in  Fig.  6.     It  is  observed  that  the  decrease  in  shrinkage 


28 


Original  Communications:  Eighth  International        [VOL. 


observed  at  0.04  per  cent,  is  due  not  to  a  decrease  in  the  total 
water  but  to  an  increase  in  the  volume  of  pore  water.  It  would 
seem  then  that  the  arrangement  of  the  clay  particles  in  the  dry 
state  is  affected  by  the  reagent,  resulting  in  a  less  compact  struc- 
ture. 

The  effect  of  Na2SC>4,  considered  by  Rohland  to  be  neutral,  was 
to  increase  the  shrinkage  decidedly  as  is  indicated  in  the  curve 


PERCENT  NfitSO,  IN  TERMS  or  SKY  T£NAl£53eE  BALL  CLAY 
Figure  7. 

of  Fig.  7,  referring  to  Tennessee  ball  clay.  The  maximum  shown 
in  the  first  part  of  the  curve  cannot  be  explained  satisfactorily  at 
this  time.  From  Fig.  8,  it  is  seen  that  the  greater  shrinkage  is  due 
to  the  increase  in  shrinkage  water  at  the  expense  of  the  pore  water. 
The  clay  grains  are  thus  separated  more  widely  from  each  other 
in  the  plastic  state  but  arrange  themselves  more  compactly  upon 
drying.  The  effect  of  BaCl2,  upon  Tennessee  ball  clay,  Fig.  9, 
seems  to  be  more  complicated  than  the  preceding  cases.  One  well 
marked  and  a  slighter  maximum  point  are  noted.  Larger  quanti- 
ties of  the  reagents  bring  about  a  second  reduction  in  shrinkage 


v] 


Congress   of  Applied  Chemistry 


29 


go 


B 

>o 

£ 

I70 


Water 


V  107  /« 

too  GRAV&   T£NN£33E£  BALL  CLA  Y 


A78 


Figure  8. 


AY  VOLUME. 
c, 


Cirve 


PERCENT &aCl,.-2htO  IN  TERMS  Or  DRY   TENNESSEE  BALL  CLAY 

Figure  9. 


30 


Original  Communications:  Eighth  International       [VOL. 


followed  -by  a  third  increase  after  which  the  drying  contraction 
appears  to  remain  constant.  From  the  volume  relations,  Fig.  9, 
it  is  apparent  that  the  reduction  in  shrinkage  is  due  to  the  diminu- 
tion of  the  amount  of  total  water  which,  at  the  end  of  the  series 
is  counteracted,  in  part,  by  the  conversion  of  pore  water  into 
shrinkage  water. 


Shrink-aye    Water 


Pore. 


Water 


«  ,.  SI  *| 


BACIt   PE*R  /OO  GRAM3  OF  TENNESSEE  BALI.  CLAY 

Figure  10. 

Summary:  The  relation  between  the  water  content  and  the 
drying  shrinkage  (by  volume)  of  two  kaolins  and  one  ball  clay 
was  determined  for  a  series  of  conditions  ranging  from  an  ex- 
tremely dry  to  a  very  soft  consistency.  Characteristic  short  curve 
were  obtained  for  the  kaolins  and  a  long  range  for  the  ball  clay. 

The  effect  of  varying  concentrations  of  the  electrolytes  NaCl, 
CaCl2,  A1C13,  Na2SO4,  and  BaCl2  upon  the  drying  shrinkage  of 
plastic  Georgia  kaolin  and  Tennessee  ball  clay  was  studied.  It 
seems  unlikely  that  the  effects  of  electrolytes  upon  clays  in  the 
plastic  state  can  be  classified  according  to  such  simple  theoretical 
assumptions  as  have  been  made  by  Rohland,  owing  to  the  com- 
plex conditions  which  involve  the  presence  of  salts  in  the  natural 


v]  Congress  of  Applied  Chemistry  31 

clay,  the  phenomena  of  adsorption,  ionic  and  hydrolytic  dissocia- 
tion and  the  constantly  changing  concentration  during  drying. 

The  electrolytes  studied  in  this  work  showed  a  tendency  to 
increase  the  shrinkage  and  presumably  the  plasticity  when  pres- 
ent in  small  concentrations.  Maxima  and  minima  seem  to  occur 
in  this  connection  showing  that  extremely  small  additions  of 
reagents  suffice  to  disturb  the  equilibrium.  As  the  concentration 
of  the  electrolyte  increases  there  is  a  distinct  tendency  to  diminish 
the  shrinkage  with  an  absence  of  maxima  and  minima,  excepting 
in  the  case  of  Na2SO4  which  seems  to  increase  contraction.  The 
positive  or  negative  effect  of  the  electrolyte  is  hence  a  function 
of  the  concentration  up  to  a  limiting  point  above  which  any  addi- 
tions produce  no  further  marked  change. 

Expressing  the  concentration  of  the  electrolytes  in  moles  it  is 
found  that  the  activity  of  the  reagents  in  reducing  shrinkage  is  of 
the  order  of  their  valences. 

The  influence  of  these  salts  extends  not  only  to  the  spacing 
of  the  clay  grains  in  the  plastic  state  but  als«  to  their  structure 
in  the  dry  condition,  resulting  in  a  looser  or  more  compact 
arrangement. 


THE    PRODUCTION    OF    AVAILABLE    POTASH    FROM 
THE  NATURAL  SILICITES 

BY  ALLERTON  S.  CUSHMAN  AND  GEORGE  W.  COGGESHALL 
Washington,  D.  C. 

The  great  demand  which  has  recently  arisen  for  an  American 
supply  of  potash  in  available  form  for  agriculture,  has  stimulated 
not  only  the  search  for  new  sources  of  this  material  but  also 
experiments  on  a  large  and  practical  scale  of  operation,  in  the 
attempt  to  develop  a  method  of  making  the  vast  supply  of  potash 
locked  up  in  feldspars  and  feldspathic  rocks  either  directly  water 
soluble  or  sufficiently  soluble  in  dilute  acids  to  insure  a  product 
which  shall  be  useful  as  a  fertilizer.  The  natural  silicites  com- 
mercially available  as  sources  of  potash  are  chiefly  orthoclase  and 
leucite.  Both  of  these  minerals  are  potassium-aluminum  silicates. 
The  theoretical  formula  for  orthoclase  is  written  K2O.Al2O3.6SiO2, 
and  for  leucite  K2O.Al203.4Si02.  The  principal  sodium  feldspar 
albite,  has  the  theoretical  formula:  Na2O.Al2Oa.6Si02.  It  is  well 
known  that  these  feldspars  run  into  and  substitute  each  other  in 
various  proportions  so  that  the  products  from  different  quarries 
will  vary  widely  in  respect  to  their  soda  and  potash  contents. 
There  is  an  enormous  supply  of  feldspar  in  the  United  States, 
both  east  and  west,  which  could  be  made  economically  possible 
as  a  source  of  potash  supply,  provided  the  cost  of  production  can 
be  made  low  enough  to  compete  with  the  potash-holding  manure 
salts  which  are  at  present  so  largely  imported  from  Germany. 
Although  it  must  be  admitted  that  the  imported  potash  salts  are 
richer  in  potash  than  any  product  that  can  ever  be  made  from 
American  feldspars,  it  should  also  be  remembered  that  the  crude 
German  manure  salts  contain  large  quantities  of  chloride  and 
sulphates  of  elements  which  are  not  only  undesirable  in  the 
fertilizer  but  which  may  do  actual  harm  under  certain  conditions. 
It  is  this  fact  which  gives  encouragement  to  the  attempt  to  pro- 
duce from  American  feldspars  a  straight  potash  fertilizer  which 

3  33 


34  Original  Communications:  Eighth  International       [VOL. 

could  be  used  in  exactly  the  same  way  that  hardwood  ashes  have 
been  found  useful. 

Six  general  methods  have  been  proposed  for  decomposing  the 
natural  silicates,  in  the  effort  to  obtain  water-soluble  potash 
salts. 

I.  Adaptation  of  Natural  Agencies.    In  the  processes  of  Nature, 
the  slow  action  of  moisture  and  atmospheric  agencies,  including 
the  action  of  carbonic  acid  gas,  is  known  to  have  a  decomposing 
or  kaolinizing  action  upon  the  feldspars.    Immense  deposits  of 
feldspar  and  granitic  rocks  have  thus  been  decomposed,  with  the 
formation  of  large  beds  of  kaolin  and  clays  from  which  the  potash 
has  been  leached  into  the  surrounding  valley.    For  this  reason, 
the  valleys  between  feldspathic  and  granitic  hills  are  usually 
highly  productive  of  the  crops  which  require  large  amounts  of 
potash,  such  as  tobacco,  potatoes,  large  fruits,  berries,  etc.    There 
have  been  a  few  processes  proposed,  which  depend  principally 
upon  the  natural   reactions  hastened  by  pressure   and   other 
agencies.    In  1904  Blackmore  (U.  S.  Patent  772,206)  proposed 
the  action  of  carbon  dioxide  gas  under  five  hundred  pounds  pres- 
sure upon  a  cream  of  the  ground  mineral,  repeated  intermittently 
for  several  hours,  in  the  attempt  to  produce  a  yield  of  carbonate 
of  potash.    Ten  years  earlier  the  same  experimenter  (U.  S.  Patent 
513,001)  had  proposed  using  lime,  calcium  chloride  and  steam 
pressure  in  an  autoclave  to  produce  chloride.     In  1910  Coates 
(U.  S.  Patent  947,795)  proposed  the  addition  of  bacteria  for  the 
decomposition  of  feldspar.     In  1910  Carpenter  (U.  S.  Patent 
959,841)  proposed  to  heat  the  mineral  intensely  and  cool  suddenly 
by  plunging  in  water,  in  the  effort  to  render  the  feldspar  amor- 
phous, in  the  hope  of  making  it  more  available  for  plant  growth. 
None  of  the  above  processes  have  as  yet  been  shown  to  possess 
industrial  possibilities. 

II.  Wet  Processes  of  a  Chemical  Nature.    Levi  in  1904  (French 
patent  344,246  and  English  patent  13,875)  and  Piva  in  1905 
(French  patent  351,338)  proposed  methods  for  treating  leucite 
by  means  of  solutions  of  alkali  or  alkali  earth  hydrates,  generally 
under  increased  pressure.    The  same  general  method  for  treating 
feldspar  was  claimed  by  Swayze  in  1907  (U.  S.  patent  862,676) 
and  by  Gibbs  in  1909  (U.  S.  patent  910,662). 


v]  Congress   of  Applied  Chemistry  35 

Also  Gibbs  in  1904  (U.  S.  patents  772,612  and  772,657)  pro- 
posed a  process  of  treatment  with  hydrofluosilicic  acid,  and  sub- 
sequently with  sulphuric  acid,  in  order  to  produce  potassium 
sulphate.  In  1907  Cushman  was  granted  U.  S.  patent  851,922, 
a  public  patent  which  proposed  the  sludging  of  finely  ground 
feldspar  with  water,  the  addition  of  a  small  amount  of  hydro- 
fluoric acid  and  electrolyzing  the  mixture  in  wooden  cells  pro- 
vided with  wooden  diaphragms.  Under  this  process  both  potas- 
sium and  aluminum  hydrate  passed  through  the  cell  diaphragm 
into  the  cathode  compartment.  This  process,  although  perfectly 
practical,  has  not  yet  been  made  commercially  possible  owing  to 
the  high  cost  of  hydrofluoric  acid  and  the  large  amount  of  by- 
products formed  in  the  process.  None  of  the  above  processes 
have  as  yet  been  made  commercial  possibilities. 

III.  Dry  Processes  of  a  Chemical  Nature,  in  which  the  Potash 
Salts  are  Volatilized.  In  processes  of  this  nature,  fluxes,  and  in 
some  cases  fuel,  for  reducing  purposes  is  ground  and  mixed  with 
the  feldspar,  the  mixture  being  subsequently  heated  until  the 
potash  salts  are  volatilized  and  collected  either  in  the  stack  dust 
or  partially  collected  from  the  gases  by  passing  them  through  or 
over  water.  Swayze  in  1905  (U.  S.  patent  789,074)  heated 
ground  feldspar  with  gypsum  and  carbon,  and  proposed  to  collect 
the  volatilized  sulphate.  Spencer  and  Eckel  in  1909  (U.  S.  patent 
912,266)  made  a  cement  mixed  with  calcareous  and  silicious 
fluxes  and  green  sand,  a  natural  potash-bearing  iron  silicate, 
clinkered  the  mixture  in  a  rotary  cement  furnace,  and  obtained  a 
Portland  cement,  at  the  same  time  collecting  the  potash  in  the 
stack  dust  and  the  flue  gases.  In  1911  Eckel  (U.  S.  patent 
1,011,172)  proposed  a  somewhat  similar  method  but  heated  only 
high  enough  to  drive  off  the  potash  salts  and  not  high  enough  to 
clinker  the  mixture.  Again  in  1911  Eckel  (U.  S.  patent  1,011,- 
173)  melted  a  mixture  of  green  sand,  limestone  and  fuel,  tapped 
off  the  melted  iron  and  slag,  and  recovered  the  potash  salts  from 
the  flue  gases. 

Some  of  the  processes  under  this  heading  have  been  tried  on  a 
large  scale.  No  great  difficulty  is  recorded  in  driving  off  the 
potash  in  the  furnaces;  but  obstacles  were  encountered  in  the 
attempt  to  collect  the  potash  from  the  gases.  As  a  by-product 


36  Original  Communications:  Eighth  International       [VOL. 

operation  in  the  manufacture  of  cements,  these  processes  may 
yet  come  to  be  of  some  industrial  importance. 

IV.  Dry  Processes  which  Propose  to  Separate  Potash  as  Hydrox- 
ide or  Carbonate.    The  old  method  of  Bickell,  proposed  in  1856,  (U. 
S.  patent  16,111),  which  depended  upon  heating  a  mixture  of  felds- 
par, lime,  and  natural  phosphate  rock  or  guano  to  a  bright  red  heat, 
has  not  as  yet  been  proved  practical  or  successful.    The  process 
of  the  Soc.  Romana  Solfati  in  1905  (French  patent  352,275), 
which  proposes  the  roasting  of  leucite  with  carbonate,  hydrate 
or  nitrate  of  soda  and  lime  and  subsequently  the  passage  of  steam 
through  the  roasted  product  to  produce  sodium  aluminate  and 
potassium  carbonate,  is  possible  from  a  chemical  standpoint  but 
the  high  cost  of  operation  has  not  permitted  the  process  to  come 
into  commercial  use. 

V.  Dry   Processes   Producing  the  Chloride.     These  processes 
have  been  most  experimented  with  upon  the  mill  scale  of  opera- 
tion. 

In  1900  Rhodin  (U.  S.  patent  641,406)  and  in  1901  (J.  Soc. 
Chem.  Indus.  XX,  439)  proposed  fritting  feldspar  with  lime  and 
salt.  According  to  the  published  results;  this  experimenter  ob- 
tained good  yields  although  the  process  has  not  become  a  com- 
mercial success.  In  1907  McKee  (U.  S.  patent  869,011)  sug- 
gested heating  a  potash-bearing  material  containing  mica  with 
lime,  salt  and  carbon  in  order  to  obtain  a  yield  of  potassium 
chloride.  Cushman  in  1911  (U.  S.  patent  987,436)  proposed 
mixing  feldspar  with  lime  and  salts  of  a  mineral  acid  capable  of 
decomposing  the  silicate,  giving  the  mixture  special  treatment 
previous  to  heating  in  a  rotary  furnace  in  order  to  produce  the 
chloride.  This  method  has  been  tried  out  on  a  large  mill  scale  of 
operation,  and  the  results  obtained  will  be  discussed  later  on  in 
this  paper. 

VI.  Dry  Processes  Producing  Sulphates.     In  1911  Thompson 
(U.  S.  patent  995,105)  proposed  heating  to  a  bright  red  heat  a 
mixture  of  feldspar,  sodium  acid  sulphate  and  sodium  chloride, 
and  subsequently  leaching  out  the  potassium  sulphate  produced. 
This  experimenter  claims  that  potassium  chloride  is  first  formed, 
which  is  subsequently  changed  to  the  sulphate  by  the  action  of 
the  acid  sulphate.     It  is  stated  that  this  process  has  recently 


v]  Congress  of  Applied  Chemistry  37 

been  tried  on  a  commercial  scale  of  operation.  Sodium  acid  sul- 
phate is  a  by-product  that  is  reasonably  cheap  although  a  large 
quantity  is  not  available.  The  lack  of  an  abundant  supply  of 
acid  sulphite  is  perhaps  the  greatest  drawback  to  the  commer- 
cializing on  a  large  scale  of  this  process,  although  it  is  possible 
that  it  may  still  become  of  some  industrial  importance.  Hart  in 
1911  (U.  S.  patent  997,671)  proposed  to  fuse  feldspar  with  some 
barium  compound,  such  as  the  sulphate,  together  with  carbon,  to 
pulverize  the  cool  melt  and  subsequently  to  digest  the  product 
with  sulphuric  acid  and  thus  produce  in  solution  potash  alum  and 
a  residue  of  barium  sulphate  and  silica  which  is  claimed  to  be 
useful  as  a  paint  pigment.  Hart  claims  that  some  of  the  potash 
is  volatilized  during  fusion.  Since  the  fusion  temperature  is 
1500°  C.,  it  is  probable  that  a  considerable  portion  of  the  potash 
does  volatilize,  and  it  is  possible  that  this  difficulty  may  interfere 
with  the  commercial  success  of  the  process. 

Wadman  in  1907  (U.  S.  patent  847,856)  proposed  heating 
lepidolite  with  potassium  sulphate  and  leaching  the  product  with 
sulphuric  acid  in  order  to  obtain  sulphates  of  lithium  and  potash. 

A  chronological  list  of  the  patents  which  have  been  granted  for 
the  treatment  of  the  silicates  for  the  production  of  available 
potash  is  given  in  Table  I. 


38  Original  Communications:  Eighth  International        [VOL. 


TABLE  I.     Proposed  Extraction  Processes  Chronologically 

Arranged 


Patentee 

Year 

Process 

Product 

IV 

Bickell 

1856 

Lime,  Ca3(PO4)2  red  heat 

Caustic 

I 

Blackmore 

1894 

Lime,  powdered  CaCl2,  H2O, 

steam 

KC1 

V 

Rhodin 

1900 

Lime,  salt,  heat  under  melt- 

ing 

KC1 

II 

Levi  (leucite) 

1904 

Ca(OH)2  or  NaOH,  pres- 

sure 16  atmospheres 

K  silicate 

II 

Gibbs 

1904 

H2SiF6  and  H2SO4 

K2S04 

I 

Blackmore 

1904 

CO2  500  Ib.  pressure  repeat- 

ing 

K2CO3 

II 

Piva 

1905 

(Leucite)     KOH,     NaOH, 

K  silicate 

steam  25  atmospheres 

K  aluminate 

IV 

Soc.  Romana  Sol- 

fati 

1905 

(Leucite)     alkali,     carbon, 

CaO  red  heat 

K2C03 

III 

Swayze 

1905 

Gypsum  and  carbon,  fuse, 

volatilize 

K2SO4 

VI 

Wadman 

1907 

Lepidolite,  K2SO4  H2SO4 

K2S04 

II 

Cushman 

1907 

Water  and  HF1  electrolysis 

KOH 

II 

Swayze 

1907 

Heat  alone  then  KOH  solu- 

K silicate 

tion 

K  aluminate 

V 

McKee 

1907 

"  containing    mica  "    with 

CaO,  NaCl  and  C 

KC1 

II 

Gibbs 

1909 

Ca(OH)2  steam  150  Ibs. 

KOH 

III 

Spencer  and  Eckel 

1909 

Green  sand  cement  mix  vol- 

atilize 

K  salts 

I 

Coates 

1910 

Bacterial  action 

I 

Carpenter 

1910 

Intense  heat,  sudden  cool- 

ing alone 

V 

Cushman 

1911 

CaO,    CaCl2   etc.,    clumps, 

red  heat 

KC1 

VI 

Thompson 

1911 

NaHSO4,  NaCl  bright  red 

K2SO4 

VI 

Hart 

1911 

Ba    compound    as    BaSO4 

and  C,  fuse,  H2SO4 

Alum 

III 

Eckel 

1911 

Cement  mix  but  not  over 

900°  C.  with  green  sand 

K2O 

volatilize 

K2S04 

III 

Eckel 

1911 

Green  sand,  CaCO  and  C. 

melt  iron  volatilize 

K2S04 

v]  Congress  of  Applied  Chemistry  39 

It  would  appear  that  the  most  promising  processes  for  making 
potash  available  from  the  natural  silicates  on  a  commercial  scale 
of  operation  are  those  which  are  conducted  in  the  dry  way  but 
without  actual  fusion  of  the  reacting  mixture.  Potash  salts  volat- 
ilize readily  at  the  high  temperatures  necessary  for  the  fusion  of 
the  silicates,  and  the  collection  of  the  volatilized  potash  from  the 
stack  gases  has  not  yet  been  carried  out  economically.  A  con- 
siderable portion  of  the  potash  does  not  settle  in  the  dust  chamber 
and  if  water  sprays  are  used  for  washing  the  gases,  the  potash 
solutions  are  very  dilute  and  the  cost  of  evaporation  becomes 
prohibitive.  Furthermore,  water  sprays  are  found  to  interfere 
with  the  draft  regulation,  even  when  the  use  of  fans  is  resorted  to. 
The  maintenance  of  artificial  draft  is  an  expensive  and  difficult 
matter,  and  is  very  likely  to  interfere  with  the  proper  control  of 
the  furnace  temperatures.  For  work  on  the  large  scale  of  mill 
operation,  a  continuous  process  must  be  used,  avoiding  fusion 
and  with  the  regulation  of  temperature  to  the  exact  point  at 
which  appreciable  quantities  of  potash  do  not  volatilize.  The 
fluxes  and  reacting  substances  must  be  cheap,  available  in  large 
quantity,  and  the  yields  of  water  soluble  potash  salts  must  be 
high.  The  process  which  has  seemed  to  us  to  give  the  most  prom- 
ise of  successful  adaptation  to  commercial  ends  is  that  of  Gush- 
man  (U.  S.  patent  987,436)  coupled  with  the  method  of  prepara- 
tion of  the  materials  before  furnacing,  proposed  and  developed 
by  Coggeshall  (U.  S.  patent  987,554). 

This  process  has  recently  been  given  extensive  trials  on  a  large 
scale  and  interesting  results  have  been  obtained.  The  process 
consists  essentially  in  powdering  100  parts  of  potash  feldspar  rock 
together  with  about  20  parts  of  lime  and  with  or  without  10  to  20 
parts  of  rock  salt.  This  powdered  mixture  is  fed  to  the  top  of  a 
moving  drum  about  three  feet  in  diameter,  in  a  layer  about  half 
an  inch  deep.  As  soon  as  the  layer  is  formed  a  strong  solution  of 
calcium  chloride  is  applied  from  a  series  of  small  tubes.  The 
CaCl2  at  once  unites  with  the  lime  forming  a  so-called  oxy- 
chloride  cement  and  a  large  portion  of  the  mixed  powder  is  there- 
by at  once  formed  into  "  clumps  "  or  aggregates  lying  in  a  bed  of 
surplus  powder.  As  the  drum  revolves  the  bed  is  removed  by  a 
scraper  to  a  belt  which  delivers  the  mixture  to  a  screen  which 


40  Original  Communications:  Eighth  International        [VOL. 

separates  the  clumps  from  the  residual  powder.  The  powder  is 
returned  by  a  screw  conveyor  and  elevator  to  the  hopper  above 
the  drum  again.  The  clumps  are  about  the  size  of  peas  and  pass 
from  the  screen  directly  to  a  rotary  kiln  similar  to  those  used  in 
burning  Portland  cement.  The  kiln  is  heated  by  a  blast  of  air 
and  powdered  coal  in  the  usual  manner. 

The  clumps  pass  regularly  down  through  the  increasingly 
heated  portions  of  the  rotating  kiln  and  roll  out  at  the  end,  prac- 
tically without  alteration  in  size  and  shape. 

A  large  percentage  of  the  total  potash  present  in  the  feldspar 
is  converted  into  potassium  chloride  during  the  heat  treatment, 
and  very  little  is  volatilized.  The  dry  clumps  are  of  a  pale  yellow 
color  outside,  due  to  the  iron  in  the  ash  of  the  bituminous  coal 
used,  but  they  are  snow  white  inside.  The  clumps  are  finally 
ground,  producing  a  pale  yellow  material  containing  as  much 
water-soluble  K20  as  hardwood  ashes,  although  the  potash  is  in 
the  form  of  chloride,  and  the  product  also  contains  considerable 
free  lime.  Up  to  the  present  time  no  attempt  has  been  made  on 
a  large  scale  to  leach  out  the  soluble  potash.  The  ground  material 
is  being  given  field  tests  as  a  straight  potash  fertilizer  containing 
lime. 

A  Resume  of  the  Large  Scale  Experiments.  Potash  Feldspars 
were  obtained  from  five  different  localities.  Eleven  carloads  were 
used  in  the  trials,  amounting  to  a  total  of  385  tons.  Each  carload 
was  ground  and  analyzed  separately.  The  lowest  in  potash  ran 
6  per  cent.  K20  and  3  per  cent.  Na^O,  the  highest  11.3  per  cent. 
K20  and  3.1  per  cent  Na2O.  The  bulk  of  the  spar  ran  10  per  cent, 
potash  and  2  per  cent,  soda,  and  the  results  given  in  this  paper 
were  obtained  on  the  10  per  cent.  spar. 

The  lime  was  a  high  calcium  quick-lime,  running  about  90  per 
cent.  CaO  and  5.6  per  cent.  MgO. 

The  salt  was  rock  salt  from  New  York  State  and  ran  about  98 
per  cent.  NaCl. 

The  calcium  chloride  was  obtained  from  the  Solvay  Process 
Company.  It  was  in  the  solid  form  and  contained  about  75  per 
cent.  CaCl2  and  25  per  cent,  water. 

All  of  the  above  materials  are  available  in  very  large  quantities 
and  at  low  cost.  The  calcium  chloride  is  a  by-product  in  the  form 


v]  Congress   of  Applied  Chemistry  41 

of  a  moderately  strong  solution,  and  but  a  small  proportion  is 
concentrated  at  the  present  time,  as  the  chief  use  is  for  refrigerat- 
ing purposes.  Vast  quantities  are  now  run  to  waste.  The  solid 
form  was  used  in  these  trials  merely  for  convenience. 

Many  heats  were  made  with  mixtures  of  varying  proportions, 
but  the  two  mixtures  used  in  the  work  here  described  were : 

Feldspar       100  Feldspar          100 

Lime  20  Lime  20 

Salt  10  Salt  20 

The  feldspar,  lime  and  salt  were  separately  crushed  in  gyratory 
crushers  and  rolls,  and  dried  in  a  rotary  drier.  In  continuous 
work  the  proper  mixture  would  be  made  at  this  point  by  con- 
tinuous weighing  machines,  but  as  a  number  of  different  mix- 
tures were  to  be  tried,  each  of  the  three  raw  materials  was  ground 
separately  in  Huntington  mills  and  put  into  bins.  This  pre- 
liminary grinding  of  the  feldspar  and  salt  was  to  about  65  per 
cent,  through  a  100-mesh  sieve,  of  the  lime  about  83  per  cent, 
through  the  100-mesh.  The  weight  per  cubic  foot  of  each 
powder  of  the  above  fineness  was  then  ascertained  and  measur- 
ing boxes  were  built  so  that  the  materials  could  be  separately 
measured  out  and  run  together  into  a  large  mixing  machine. 
Almost  a  ton  was  thus  mixed  each  time.  The  mixture  was  then 
conveyed  to  a  tube-mill  and  further  ground  to  a  fineness  of  from 
97  per  cent,  to  99.5  per  cent,  through  a  100-mesh  sieve,  and 
then  conveyed  to  the  bin  over  the  clumper  and  kiln. 

The  calcium  chloride  masses  were  broken  up  and  thrown  on  a 
perforated  grid  in  a  large  tank  holding  about  48  tons.  Water  was 
run  in  and  the  chloride  dissolved  most  readily.  The  solution  was 
run  out  when  about  42  degrees  Beaume  into  two  large  sump  tanks, 
and  brought  to  a  constant  strength  of  about  42  per  cent.  CaCl2. 
This  was  then  pumped  up  to  an  elevated  tank  and  piped  from 
there,  through  a  constant-level  tank,  to  the  dropper  tubes  of  the 
clumper  placed  in  a  row  above  the  drum.  This  drum  is  15.5  feet 
long  and  3  feet  in  diameter,  and  is  horizontal.  There  are  15 
valved  pipes,  each  one  feeding  an  adjustable  pipe  holding  38  short 
dropping  tubes  of  brass  Y&  incn  internal  diameter,  and  set  -£$  inch 
apart. 


42  Original  Communications:  Eighth  International        [VOL. 

The  finely  ground  mixed  powder  is  taken  from  the  bin  by  a 
chute,  elevator  and  screw  conveyor  and  distributed  in  a  long 
hopper  trough  over  the  drum.  It  is  taken  from  the  trough  by  a 
roll  device  and  spread  evenly  on  the  moving  drum  at  its  topmost 
point.  The  drum  has  a  surface  velocity  of  about  1.6  inches  per 
second,  the  layer  of  powder  advancing  at  this  rate. 

It  was  found  that  by  dropping  the  liquid  very  rapidly  upon  the 
powder,  the  clumps  could  be  made  rapidly  enough  to  give  a  full 
feed  to  the  short  rotary  kiln  when  only  one-third  of  the  trough 
and  droppers  and  drum  is  used.  A  clumper  drum  5  feet  long 
produces  every  hour  almost  two  tons  of  fresh  clumps  and  con- 
siderably over  a  ton  and  a  half  of  burned  product  with  the  kiln 
used  in  these  trials.  The  excess  of  powder  passes  through  a 
screen  and  goes  to  the  same  elevator  which  lifts  the  original 
material  from  the  bin.  The  amount  of  actual  CaCl2  in  the  fresh 
lime  is  regulated  to  about  20  parts  to  each  100  parts  of  feldspar 
in  the  mixture.  The  clumps  leave  the  screen  in  rounded  form 
and  flow  directly  into  the  kiln. 

The  reason  for  the  above  procedure  will  now  be  explained.  In 
the  first  place,  calcium  chloride  reacts  very  efficiently  under  these 
conditions  with  the  feldspar  by  replacing  the  potassium  with 
calcium,  thus  forming  calcium  silicate  and  potassium  chloride. 
Anhydrous  calcium  chloride  is  expensive  to  produce  and  it  is  im- 
practicable to  grind  it  into  a  mixture  on  a  large  scale  on  account 
of  the  rapid  absorption  of  moisture.  Even  if  such  a  dry  mixture 
could  easily  be  made,  its  use  would  present  certain  disadvantages. 

When  a  reaction  between  an  ore  and  solid  fluxes  is  produced  by 
heating  up  to  the  fusing  temperature,  the  reaction  takes  place  on 
the  surface  of  the  particles  alone  and  only  at  the  points  where  the 
ore  is  in  actual  contact  with  the  flux  particles.  Finer  grinding 
will  produce  a  larger  surface  area  and  thus  a  greater  number  of 
actual  contact  points,  leading  to  a  larger  yield.  There  is,  how- 
ever, a  degree  of  fineness  beyond  which  it  is  not  wise  to  go,  on 
account  of  the  cost  of  extremely  fine  grinding. 

Another  factor  in  the  problem  is  brought  out  by  the  following 
experiments.  A  batch  of  ore  and  the  theoretical  amount  of 
solid  flux  were  ground  together  to  just  pass  a  50-mesh  sieve. 
This  powder,  when  subjected  to  a  certain  heat  treatment,  gave  a 


v]  Congress  of  Applied  Chemistry  43 

reaction  yield  of  about  35  per  cent,  of  the  theoretical.  The  mix- 
ture was  then  ground  to  just  pass  a  100-mesh  sieve  and  given  the 
same  heat  treatment.  A  reaction  yield  was  obtained  of  about  65 
per  cent,  of  the  theoretical.  The  mixture  was  then  ground  to 
pass  a  200-mesh  sieve  and  again  reheated  as  before.  A  smaller 
yield  was  obtained  than  when  the  material  just  passed  the  100- 
mesh,  although  the  particles  were  undoubtedly  only  half  the 
average  diameter  with  about  four  times  the  surface  area  and 
should  therefore  have  had  far  more  points  of  contact.  Upon 
weighing  equal  volumes  of  the  50-mesh,  100-mesh  and  200-mesh 
powders,  it  was  found  that  the  latter  contained  far  less  material 
and  it  became  apparent  that  the  200-mesh  powder  consisted  for 
over  54  per  cent,  of  its  Volume  simply  of  voids.  Such  finely 
ground  powders  are  well  known  to  "surge",  that  is,  to  show  the 
tendency  to  flow  like  water  through  orifices  in  a  manner  resembl- 
ing fountains.  Material  ground  as  fine  as  this  is  the  cause  of 
much  trouble  at  spout  slides  and  conveyors.  Each  particle  of  a 
material  of  this  extreme  fineness  is  undoubtedly  surrounded  by  a 
film  of  air,  the  actual  contact  with  the  surfaces  is  lessened  and 
friction  almost  eliminated.  When  allowed  to  flow  into  a  bin, 
such  a  powder  assumes  an  almost  horizontal  surface,  there  is 
practically  no  angle  of  repose.  Unquestionably  the  lessened 
contact  caused  the  low  yields  in  the  finely  ground  mixtures. 
Some  of  the  finer  material  was  briquetted  and  the  subsequent 
heat  yield  about  85  per  cent,  of  the  theoretical.  Briquetting  is, 
however,  expensive  and  usually  necessitates  the  addition  of  a 
binding  agent  foreign  to  the  reaction. 

As  a  result  of  these  investigations,  the  method  was  developed 
for  aggregating  fine  powders  by  dropping  a  suitable  liquid  upon 
an  excess  of  the  powder  in  such  a  way  as  to  cause  a  temporary 
bond  to  form,  thus  practically  eliminating  the  air  films  or  voids 
around  the  individual  particles  and  permitting  actual  surface 
contact.  Under  these  conditions,  with  the  same  ore  and  flux  used 
in  the  experiments  described  above,  the  same  heat  treatment 
yielded  within  3  per  cent,  of  the  theoretical  quantity  present. 
This  method  of  aggregating  finely  powdered  materials  previous  to 
furnacing  has  already  been  used  in  several  different  ways.  For 
example,  in  an  ore  mixture  in  which  the  fluxing  material  is  an 


44  Original  Communications:  Eighth  International       [VOL. 

alkaline  carbonate,  such  as  sodium  or  potassium,  which  forms 
crystalline  salts  containing  water  of  crystallization,  if  the  car- 
bonate is  used  in  the  partially  anhydrous  condition  and  ground 
with  the  ore  water  alone  dropped  upon  the  mix  in  the  manner 
described  formed  at  once  a  crystalline  carbonate  which  binds  the 
particles  of  ore  and  flux  into  separate  clumps,  which  are  hard 
enough  to  withstand  screening,  while  the  air  films  are  practically 
eliminated.  Using  such  a  mixture  and  process  as  this,  a  practi- 
cally theoretical  yield  was  obtained,  although  the  flux  was  used 
only  in  the  exact  molecular  proportion  called  for  by  the  reaction. 

By  this  clumping  process  a  very  intimate  contact  of  reaction 
of  surfaces  is  readily  obtained  at  a  low  cost.  The  quantity  of 
flux  necessary  to  complete  the  reaction  is  greatly  reduced,  the 
duration  and  temperature  of  the  heat  treatment  is  lessened  and 
working  with  rotary  kilns  dusting  and  stack  losses  are  almost 
entirely  eliminated.  The  clumps  are  beautifully  adapted  to  the 
feed  mechanism  of  rotary  kilns,  as  they  flow  easily,  do  not  dust 
and  take  the  heat  more  evenly  than  fine  powders.  Now  that  the 
temperature  conditions  in  rotary  kilns  can  be  accurately  con- 
trolled, it  would  seem  that  many  chemical  and  metallurgical 
reactions  which  are  now  performed  by  intermittent  processes 
and  with  low  yields  could  be  much  more  economically  carried  out 
in  continuous  rotary  kilns,  taking  advantage  of  this  new  method 
of  forming  aggregates  previous  to  furnacing. 

In  the  application  of  this  method  to  the  treatment  of  felds- 
pathic  rock,  advantage  was  taken  of  the  fact  that  a  solution  of 
calcium  chloride  acts  upon  dehydrated  lime  to  form  the  oxy- 
chloride  which  is  a  strong  cementing  compound.  It  was  found 
that  the  formation  of  calcium  oxychloride  gave  a  sufficiently 
strong  bond  to  enable  the  aggregates  to  withstand  the  operation 
of  screening  and  the  burden  in  the  kiln. 

The  theoretical  quantity  of  calcium  chloride  flux  required 
depends  upon  the  total  quantity  of  K^O  and  Na20  present  in  the 
mix,  as  it  is  evident  that  the  soda  must  also  be  liberated  in  pro- 
portion to  its  content.  The  feldspar  ore  used  ran  10  per  cent. 
K20  and  2  per  cent.  Na2O  which  required  theoretically  15.5  parts 
of  calcic  chloride.  In  all  our  trials  some  slight  excess  of  calcium 
chloride  has  been  used.  The  strength  of  the  solution  and  the 


v]  Congress   of  Applied  Chemistry  45 

method  of  treatment  has  been  such  that  about  20  parts  of  actual 
calcium  chloride  are  present  in  the  fresh  clumps  to  every  100  parts 
of  feldspar.  The  20  parts  of  lime  used  is  for  the  purpose  of  form- 
ing the  aggregates,  and  this  lime  remains  practically  unchanged 
in  the  finished  product.  The  presence  of  lime  in  a  potash  fer- 
tilizer will  be  found  advantageous  to  most  soils,  and  it  is  generally 
admitted  that  lime  increases  the  manurial  value  of  a  fertilizer. 
If  the  object  was  to  leach  out  the  soluble  potash  salts  from  the 
product,  a  much  smaller  amount  of  lime  could  be  used  without 
interfering  with  the  formation  of  hard  clumps.  The  salt  is  added 
because  it  has  been  found  to  aid  the  heat  reaction,  probably 
mechanically  as  will  be  explained  later  on.  The  fresh  clumps 
contain  from  16  to  20  per  cent,  of  moisture,  which  is,  of  course, 
evaporated  in  the  upper  part  of  the  kiln. 

The  rotary  kiln  used  in  these  trials  was  one  of  the  old  bottle 
shape  cement  kilns  with  a  total  length  of  slightly  over  fifty-five 
feet,  the  upper  twenty  feet  having  a  diameter  of  4  feet  clear  inside 
the  firebrick  lining,  the  lower  portion  widening  out  to  nearly  6 
feet  inside  diameter.  The  pitch  was  f  inch  per  foot  and  the  most 
suitable  speed  was  found  to  be  one  revolution  in  about  2  J  minutes. 

The  conditions  of  the  heat  treatment  are  very  important.  The 
kiln  used  was  too  short  to  yield  the  best  results,  and  after  the 
preliminary  experiments  changes  were  made  which  caused  the 
material  to  take  about  If  hours  to  pass  through  the  length  of  the 
kiln.  The  temperature  of  the  gases  issuing  from  the  upper  end 
of  the  kiln  were  read  continually  with  a  thermo-couple  pyrometer 
fitted  with  a  15-foot  fire  end  and  temperatures  were  also  taken 
from  time  to  time  at  the  firing  platform.  A  furnace  wall  tem- 
perature of  about  1370°  C.  is  required  for  efficient  burning  of 
powdered  bituminous  coal.  This  is,  however,  much  too  high  a 
temperature  for  potash  work  in  a  rotary  kiln.  This  difficulty 
called  for  careful  experimental  investigations  and  adjustments 
of  the  heat  treatment  before  the  proper  yields  could  be  obtained. 
If  a  longer  kiln  had  been  available,  there  is  every  reason  to  be- 
lieve that  a  more  efficient  use  of  the  heat  could  have  been  ob- 
tained. The  coal  used  was  a  fairly  high  volatile  bituminous  coal. 
It  was  ground  to  about  94  per  cent,  through  a  100-mesh  sieve  and 
blown  into  the  furnace  under  an  air  pressure  of  about  ten  pounds 
per  square  inch. 


46  Original  Communications:  Eighth  International       [VOL. 

During  the  progress  of  the  clumps  down  the  kiln  the  following 
reactions  probably  take  place.  At  the  entrance  to  the  kiln  the 
water  begins  to  evaporate.  As  the  hotter  zone  is  approached,  the 
temperature  rises  high  enough  to  melt  calcium  chloride  and  salt. 
Whether  the  calcium  chloride  is  free  to  melt  is  not  known  to  us, 
as  the  exact  composition  of  the  oxychloride  compound  formed 
has  not  yet  been  determined.  The  results  of  our  work  seem  to 
prove  that  the  reacting  chlorine  is  more  readily  evolved  from  the 
oxychloride  compound  than  it  is  from  calcium  chloride  alone. 
The  melting  of  the  salt,  however,  continues  the  bond  of  the  re- 
acting particles,  causing  them  to  thoroughly  "  wet  "  each  other, 
and  from  this  point  on  the  attact  on  the  silicate  proc.eeds  rapidly. 
During  the  heating  usually  from  1  to  2  per  cent,  of  Na2O  is  volat- 
ilized. 

When  operating  with  no  salt  present,  the  yield  of  soluble  potas- 
sium chloride  was  47.5  per  cent,  of  that  originally  present  in  the 
feldspar.  On  adding  to  the  mixture  10  parts  of  salt  to  each  100 
of  spar,  a  test  heat  yielded  64  per  cent,  but  of  this  9  per  cent,  was 
lost  by  volatilization,  giving  a  yield  of  55  per  cent,  net  in  the 
final  product.  On  adding  20  parts  of  salt  to  the  mixture  the 
yield  grows  to  69.2  per  cent,  with  no  volatilization  and  to  75  per 
cent,  under  heat  conditions  which  caused  a  volatilization  of  7  per 
cent.,  leaving  a  net  yield  of  68  per  cent,  of  that  originally  present. 
In  the  case  of  clumps  made  from  a  mixture  of  100  parts  of  feldspar 
containing  10  per  cent.  K2O  and  2  per  cent.  Na20,  20  parts  of 
lime,  20  parts  of  salt  and  20  parts  of  calcium  chloride,  the  theo- 
retical composition  if  no  volatilization  loss  takes  place  is  shown 
compared  with  the  actual  results  obtained  in  the  following  table. 

Theory     Analysis 

Total  K2O  6.25%     5.8% 

Water  soluble  K20  ....     4.2%       Equals  6.65%  KC1 

Loss  of  K2O  5%       As  KC1  already 

formed 

Total  Na2O  7.62%      7.1%       52%  made  into  NaCl 

Water  soluble  Na20  6.37%  5.1%  Showing  1.79%  vapor- 
ized as  NaCl  or  26% 
of  that  present 


Congress  of  Applied  Chemistry 


47 


This  particular  product  contained  11.2  per  cent,  of  free  lime 
and  total  lime  by  analysis  15.5  per  cent.  There  was  also  in  this 
sample  about  5  per  cent,  of  free  unchanged  calcic  chloride.  The 
amount  of  calcic  chloride  in  the  various  runs  made  up  to  the 
present  time  have  been  reduced  gradually  to  about  1  per  cent., 
and  it  is  felt  that  in  the  future  better  conditions  of  heat  treat- 
ment will  make  complete  use  of  the  calcic  chloride  and  at  the 
same  time  raise  the  yields  of  soluble  potash.  In  later  runs  in 
which  only  10  parts  of  salt  were  present  in  the  mix,  the  theoretical 
and  actual  analysis  of  the  product  was  as  follows : 


Total  K2O 

Water  soluble  K20 

Vaporization  loss  of 

soluble  K20 
K2O  insoluble  in  water 
Total  Na2O 
Water  soluble  Na2O 


Theory     Analysis 


6.66% 


4.15% 


5.62% 

4.5% 

1.04% 
1.12% 

3.7% 


Equals  7.12%  KC1 
As  KC1  already 
formed 


Showing  0.45%  vapor- 
ized as  NaCl  or  11% 
of  that  present 


This  product  contained  12.25  per  cent,  of  free  lime,  the  total 
potash  rendered  soluble  was  5.54  per  cent,  of  the  product  or  83.2 
per  cent,  of  the  total  quantity  present,  but  as  15.6  per  cent,  had 
been  volatilized  the  net  yield  in  the  product  amounted  to  57.6 
per  cent. 

The  material  which  was  later  made  continuously  according  to 
the  process  described  above  carries  4.5  per  cent,  of  water  soluble 
K2O  in  the  form  of  7.12  per  cent,  potassium  chloride  and  in  addi- 
tion to  this  material  carries  only  1.12  per  cent.  K2O  insoluble  in 
water.  It  is  well  known  that  a  2  per  cent,  citric  acid  solution  will 
extract,  when  used  according  to  the  Wagner  method  somewhat 
more  K20  than  can  be  made  directly  water  soluble.  This  fact  is 
of  considerable  interest  when  the  product  is  to  be  used  directly 
as  a  potash  fertilizer. 

Conclusion.  It  is  believed  that  under  better  conditions  of  heat 
treatment  which  can  be  obtained  with  longer  kilns  and  with  a 
somewhat  different  arrangement  of  the  combustion  chamber, 


48  Original  Communications:  Eighth  International       [VOL. 

that  slightly  better  yields  than  those  reported  can  be  obtained. 
It  should  be  remembered  that  the  kiln  used  in  these  experimental 
trials  was  originally  designed  for  burning  cement,  but  this  type  of 
kiln  has  long  been  superseded  by  improved  forms.  In  order  to 
get  the  proper  heat  treatment  in  the  middle  of  the  kiln  to  com- 
plete the  reaction,  it  was  necessary  to  have  the  upper  part  too 
hot.  This  condition  will  not  maintain  in  a  properly  designed 
kiln.  It  is  also  believed  that  the  use  of  oil  as  fuel  would  have 
allowed  an  easier  regulation  of  the  heat  treatment  but  the  trials 
so  far  undertaken  have  been  made  under  conditions  which  were 
found  available  at  the  time. 

The  subject  of  the  costs  of  this  process  and  of  the  product 
cannot  be  gone  into  in  detail  at  this  time  but  a  few  general  state- 
ments may  be  made.  The  production  of  water  soluble  potash  in 
feldspathic  rock  is  essentially  a  low  grade  proposition,  and  the 
commercial  success  of  such  a  process  depends  upon  the  low  cost 
of  the  various  operations.  The  manufacture  of  a  straight  potash 
fertilizer  containing  as  valuable  ingredients  only  potash  and  lime 
must  be  carried  out  on  a  very  large  scale  and  by  the  most  modern 
methods  of  continuous  operation.  With  regard  to  the  clumping 
process,  the  trials  have  shown  that  this  operation  can  be  practical- 
ly carried  out  as  a  continuous  process  and  at  an  exceedingly  low 
charge  per  ton  of  product. 

The  process  may  be  directly  compared  with  that  of  the  manu- 
facture of  Portland  cement.  It  is  a  little  easier  to  grind  feldspar 
and  lime  than  the  shales  and  limestones  used  in  cement  manu- 
facture. Drying  will  cost  no  more.  Chemical  control  of  the  raw 
mixes  will  not  be  more  expensive  and  perhaps  much  less.  Clump- 
ing, as  has  been  shown,  adds  a  very  small  charge  to  the  expense  of 
treatment.  The  cost  of  furnacing  the  feldspar  mix  will  be  less 
than  similar  charges  in  the  cement  industry,  as  the  temperatures 
required  are  much  lower  and  less  coal  is  consumed.  The  product 
from  the  potash  kiln  is  comparatively  soft  and  pulverizes  easily 
in  hammer  mills,  while  the  charges  on  the  cement  industry  for 
grinding  clinker  is  an  important  item.  Again  the  softer  potash 
product  merely  requires  to  be  ground  fine  enough  for  use  as  a 
fertilizer,  whereas  cement  clinker  must  be  ground  very  fine  and 
costs  rise  rapidly  with  increasing  fineness.  Repair  bills  in  the* 


v]  Congress  of  Applied  Chemistry  49 

case  of  feldspar  treatment  should  be  much  smaller  than  in  cement 
manufacture.  The  charge  for  raw  materials  is  somewhat  larger 
than  in  the  case  of  cement  but  this  is  more  than  met  by  the 
smaller  costs  of  operation. 

The  potash  fertilizer  as  now  produced  should  be  the  equal  in 
fertilizing  value  of  the  ordinary  grades  of  hardwood  ashes.  The 
product  carries  practically  the  same  content  of  water-soluble 
potash  and  somewhat  more  lime  than  wood  ashes.  There  is 
every  reason  to  believe  that  if  the  process  becomes  an  industry 
that  the  yields  of  water  soluble  potash  can  be  considerably  im- 
proved. The  material  yielded  is  not  a  fused  product,  it  is  friable 
as  an  ash  and  it  has  the  physical  texture  to  make  it  a  valuable 
aid  to  soil  structure.  The  success  of  the  product,  must,  of  course, 
depend  upon  the  results  obtained  under  test  conditions  in  its 
experimental  use  as  a  fertilizer.  If  results  are  obtained  which 
are  as  good  or  better  than  those  which  usually  attend  the  proper 
use  of  high  grade  wood  ashes,  it  is  believed  that  there  should  be 
no  reason  why  this  product  cannot  be  successfully  produced  and 
introduced,  especially  in  those  parts  of  the  country  where  potash 
feldspars,  fuel  and  shipping  facilities  are  available. 

Summary.  In  this  paper  a  summary  is  given  of  the  various 
processes  which  have  been  proposed  for  making  the  potash  in  the 
natural  silicates  available  as  a  fertilizer. 

Experimental  trials  of  a  new  rotary  kiln  process  for  treating 
feldspar  are  described,  which  depends  upon  a  previous  treatment 
before  f urnacing,  consisting  of  a  method  of  aggregating  or  clump- 
ing the  mix  so  that  chemical  contact  of  the  reacting  substances 
is  brought  about  during  the  subsequent  processing.  The  quali- 
tative and  quantitative  results  obtained  on  a  number  of  experi- 
mental trials  on  a  mill  scale  of  operation  are  presented  and  dis- 
cussed. It  is  shown  that  it  is  possible  to  economically  manu- 
facture a  potash  fertilizer  containing  free  lime  from  feldspar  and 
for  a  sufficiently  low  cost  to  make  an  industry  based  upon  the 
method,  worthy  of  consideration. 
4 


NOTES  ON  A  STUDY  OF  THE  TEMPERATURE  GRAD- 
IENTS OF  SETTING  PORTLAND  CEMENT 

BY  ALLEETON  S.  CUSHMAN 
The  Institute  of  Industrial  Research,  Washington,  D.  C. 

The  reactions  that  take  place  when  hydraulic  cements  are 
tempered  with  water  and  while  the  mixture  is  hardening  are  as 
yet  not  understood.  It  is  true  that  many  theories  have  been 
advanced  in  regard  to  the  hardening  process  or  processes  but 
more  data  is  required  before  much  that  now  seems  inexplicable 
can  be  understood. 

Since  all  chemical  reactions  are  accompanied  by  definite  and 
measurable  thermal  changes,  complete  temperature  records  of 
hardening  cements  should  yield  interesting  and  valuable  data. 

It  is  well  known  that  if  a  portland  cement  clinker  is  ground 
without  the  addition  of  from  2  to  3  per  cent,  of  calcic  sulphate  or 
gypsum  to  act  as  a  restrainer  it  will  be  "  flashy."  By  "  flashy  " 
is  meant  the  tendency  to  harden  very  quickly,  so  quickly  in  fact 
that  in  many  cases  it  is  impossible  to  mold  the  wetted  cement 
into  a  plastic  mass.  While  this  sudden  hardening  is  going  on,  a 
considerable  amount  of  heat  is  generated  so  that  the  mass  feels 
hot  to  the  hand.  The  temperature  rises  about  10°  to  15°  C.  but 
the  heat  reaction  lasts  only  a  short  time  and  after  cooling  no 
further  heat  reaction  takes  place.  When  however,  a  portland 
cement  has  been  properly  restrained  by  grinding  with  it  2  or  3 
per  cent,  of  gypsum  (plaster)  the  conditions  of  thermal  activity 
are  changed  in  a  quite  extraordinary  manner.  On  mixing  a  nor- 
mal Portland  Cement  with  sufficient  water  to  form  a  normally 
plastic  mass,  a  certain  amount  of  heat  is  immediately  disengaged 
although  not  so  much  as  in  the  case  of  an  unplastered  cement. 
The  plastic  mass  soon  cools  down  to  the  air  temperature  and 
generally  falls  somewhat  below  the  surrounding  temperature 
showing  that  a  decided  cooling  effect  is  taking  place.  If  now  the 
plastic  mass  is  allowed  to  stand  quiescent  in  a  constant  tempera- 
ture chamber,  nothing  of  moment  happens  if  the  cement  be  a 

51 


52  Original  Communications:  Eighth  International        VOL. 

normal  standard  brand,  for  a  period  of  from  four  to  eight  hours. 
At  a  given  time  however,  for  every  mixture  a  secondary  heat  rise 
begins,  and  increases  more  or  less  rapidly  to  a  definite  maximum. 
After  this  rise  is  completed  the  cement  has  attained  its  final  set 
and  a  gradual  cooling  takes  place  to  the  temperature  of  the 
surrounding  air  and  nothing  further  happens.  If  an  imperfect, 
damaged  or  lumpy  cement  is  under  observation  the  temperature 
gradient  for  the  rise  may  show  aberrations.  That  is  to  say,  a 
sudden  rise  may  be  followed  by  a  temporary  cooling  only  to  be 
followed  by  another  rise. 

The  wonderful  effect  of  a  small  percentage  of  gypsum  plaster 
in  thus  controlling  and  regulating  the  temperature  gradients  or 
reaction  of  setting  cement  is  little  understood  and  indeed  presents 
certain  anomalous  occurrences  for  our  consideration  as  will  be 
shown  later  on. 

The  first  successful  attempt  to  record  the  temperature  gradient 
of  setting  cement  as  far  as  the  writer  has  been  able  to  ascertain  was 
made  by  Gary  who  used  a  photographic  recording  device  which 
has  been  fully  described  by  Burcartz.1  The  method  consisted  of 
placing  the  bulb  of  an  ordinary  glass  thermometer  in  the  cement 
paste.  The  whole  arrangement  was  enclosed  in  a  box  through 
which  a  beam  of  light  was  made  to  impinge  through  a  slot,  upon 
the  graduated  stem  of  the  thermometer  and  then  upon  a  travelling 
photographic  film.  As  the  mercury  rose  or  fell  the  beam  of  light 
was  cut  by  the  shadow  of  the  mercury  column  and  thus  a  con- 
tinuous temperature  gradient  record  was  obtained. 

The  only  criticism  of  this  method  that  can  be  made  is  that  it 
calls  for  an  expensive  and  delicately  adjusted  piece  of  apparatus 
which  few  laboratories  would  care  to  install,  and  in  which  the 
temperature  changes  cannot  be  watched  while  they  are  taking 
place.  The  apparatus  used  by  the  writer  is  simple,  comparatively 
inexpensive  and  can  be  installed  and  used  in  any  laboratory  for 
making  daily  records.  The  apparatus  is  shown  in  Fig.  1. 

A  double  walled  wooden  box  as  shown  in  Fig.  7,  used  simply  to 
avoid  any  sudden  changes  which  may  take  place  in  the  laboratory 
temperature  during  a  test  run.  An  ordinary  so-called  "  fireless 


.  Record  Dec.  llth,  1909. 


Congress   of  Applied  Chemistry 


53 


cooker  "  such  as  can  be  bought  at  any  kitchen  supply  store 
answers  very  well  for  this  purpose.  The  recording  thermometer 
is  of  the  Tycos  type  and  consists  of  a  copper  plated  steel  tapered 
mercury  filled  bulb  9  c.  m.  long  by  about  2  c.  m.  in  its  maximum 
diameter.  The  bulb  is  connected  to  the  recording  dial  by  a 


Fiq.1- 


flexible  steel  capillary  tube.  The  recording  dial  has  a  range  from 
10%  to  120°  F.  The  recorder  is  fairly  accurate  for  the  middle 
range  and  is  easily  calibrated  and  adjustable. 
'  In  ordinary  tests  as  carried  out  in  the  writer's  laboratory  1 
kilogram  of  the  neat  cement  is  tempered  with  250  c.  c.  of  water  to 
make  a  homogeneous  plastic  paste  which  is  packed  into  a  No.  2 
open  top  tin  can.  The  thermometer  bulb  is  not  inserted  until  the 
primary  heat  effect  which  always  develops  when  cement  is 
kneaded  with  water,  is  over,  and  the  paste  reaches  approximately 
the  same  temperature  as  the  calorimeter  box.  In  the  meantime 
the  copper  plated  thermometer  bulb  is  smeared  with  vaseline  and 
wrapped  with  several  folds  of  fairly  heavy  tin  foil.  The  object 
of  these  precautions  is  two  fold;  in  part  to  guard  against  the 
"  freezing  "  in  of  the  bulb  when  the  cement  hardens  and  in  part 
to  overcome  any  possible  pressure  on  the  walls  of  the  bulb  if  the 
cement  shrinks  or  expands  during  the  hardening  process.  With 


54  Original  Communications:  Eighth  International        [VOL. 

25  per  cent,  of  water  the  consistency  is  somewhat  softer  than 
the  normal,  but  experience  has  shown  that  the  wetter  mixture 
gives  better  results  under  the  conditions  of  the  test.  When  all  is 
ready  the  covered  bulb  is  pushed  into  the  cement  paste,  care 
being  taken  that  it  is  not  pushed  below  the  surface  so  that  the 
cement  can  close  over  the  shoulder  of  the  bulb  and  so  imprison 
it  when  hardening  takes  place.  When  these  precautions  are  taken 
the  apparatus  gives  no  trouble  and  the  bulb  is  easily  withdrawn 
from  the  hard  cement  at  the  end  of  the  test.  The  temperature 
gradients  are  usually  taken  for  a  twenty-four  hour  period,  al- 
though this  is  not  necessary  unless  the  full  cooling  curve  is 
desired. 

In  presenting  these  notes  on  the  temperature  gradients  of  set- 
ting cements,  it  is  not  the  intention  of  the  writer  to  draw  any 
conclusions  at  this  time  in  regard  to  the  mechanism  of  the  harden- 
ing reactions. 

The  curves  obtained  on  the  revolving  scale  are  transferred  to 
centigrade  degrees  and  plotted  in  rectangular  coordinates  as  is 
shown  in  the  illustrations,  plates  I  and  II,  curves  1  to  32.  An 
inspection  of  the  curves  will  show  that  in  some  cases  the  tempera- 
ture gradients  are  much  steeper  and  more  sudden  than  in  others. 
Curves  6,  7,  8  and  21  represent  cases  in  which  the  water  was 
simply  poured  on  to  the  dry  cement  without  previously  kneading 
the  mass  to  a  paste.  In  no  case  of  this  kind  is  a  rise  in  tem- 
perature noted  following  the  final  set  or  hardening,  at  about  seven 
to  eight  hours. 

In  the  cases  of  some  brands  of  cement  as  is  shown  in  curves 
9,  10,  11  and  12  the  rise  in  temperature  is  constant  and  gradual  to 
a  maximum  which  usually  occurs  at  about  ten  to  eleven  hours. 
In  other  cases  notably  in  curves  17  and  29,  the  rise  is  sharp  and 
sudden.  As  both  types  of  cement  pass  muster  in  the  standard 
tests,  it  is  not  possible  at  the  present  time  to  state  what  the  ideal 
temperature  gradient  curve  for  a  cement  should  be. 

That  the  maxima  and  shape  of  the  curves  is  modified  by  the 
addition  of  various  salts  to  the  tempering  water  is  shown  in 
curves  13,  14,  15,  16,  17,  18,  19,  20  and  22. 

Perhaps  the  most  extraordinary  curve  is  number  19  which 
shows  the  heating  effect  produced  by  saturating  the  water  with 


.                                                H 

* 

h                        ? 

3 

j*~«-*t 

""                                               am  '** 

'. 

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j-^j                           «i*^v 

1 

4 

i-T^ 

J            ~ 

Plntel. 

5*6 


v]  Congress   of  Applied  Chemistry  55 

calcium  sulphate.  In  this  case  the  temperature  rose  above  the 
scale  of  the  recording  device  and  the  test  piece  became  uncomfort- 
ably hot  to  the  hand.  Since  calcic  sulphate  is  used  as  a  re- 
strainer  when  ground  with  a  cement,  this  extraordinary  effect  of 
calcic  sulphate  solution  is  difficult  to  explain. 

Curves  25,  26,  27  and  28  were  from  cements  which  did  not 
stand  test  and  had  been  rejected.  The  abnormality  of  these 
curves  is  at  once  apparent  to  the  eye  and  furnishes  the  best 
argument  as  to  the  value  of  a  study  of  the  temperature  gradient 
as  an  additional  method  of  control  in  cement  testing. 

In  conclusion  the  author  wishes  to  point  out  that  these  notes 
on  the  study  of  temperature  gradients  are  offered  not  as  data 
on  which  to  establish  theories  but  to  stimulate  other  workers  to 
include  similar  investigations  in  their  studies  of  the  hardening  of 
hydraulic  cements. 


CAUSES  OF  BREAKAGE  IN  GLASS  MANUFACTURE 
AND  METHOD  OF  DIFFERENTIATING  CHEMICO- 
HETEROGENEIC  STRAINS  FROM  COOLING  STRAINS 

BY  ROBERT  L.  FRINK 
Columbus,  Ohio 

The  manufacture  of  Glass,  as  carried  on  in  the  majority  of 
factories  wherein  pressed  ware,  table  ware,  plate  and  window 
glass  is  made,  is  conducted  in  substantially  the  same  manner, 
with  perhaps  a  few  minor  improvements,  as  has  been  the  case  for 
ages,  and  up  until  a  few  years  ago  there  had  been  no  inventions 
presented  or  improvements  made  in  the  art  for  hundreds  of  years, 
and  to-day  the  actual  making  of  the  glass,  consisting  of  the  pro- 
portioning of  the  raw  materials,  charging  them  into  and  firing 
the  furnace  for  melting  them,  shows  very  little,  if  any,  improve- 
ment, and  substantially  no  acquisition  of  knowledge  as  to  the 
real  properties  of  the  glasses,  and  the  cause  and  effect  of  modifica- 
tions, or  variable  conditions,  surrounding  and  entering  into  the 
production. 

I  have  many  times  been  asked  by  progressive  Glassmakers, 
where  they  could  obtain  literature  on  the  subject  of  control  of 
melting  furnaces  and  compositions,  to  which  I  have  been  com- 
pelled to  reply  that  I  knew  of  none.  Hovestadt,  Winkelman, 
Tillotson,  Kennedy,  Schott,  Lorentz  and  Lorenz,  and  in  an 
indirect  manner,  Wedgewood,  Pirsson,  Day,  Wright,  Rosenbusch 
and  Winchell,  have  each  furnished  us  with  more  or  less  data  on 
which  might  be  based  certain  deductions,  and  which  might  be 
assumed  or  be  attributed  as  the  effect  of  certain  causes,  but  these, 
with  the  exception  of  perhaps  a  few  experiments  of  Day,  Lorenz 
and  Hovestadt,  are  based  on  laboratory  operations  and  condi- 
tions, and  do  not  represent  and,  as  a  consequence,  do  not  reveal 
the  problems  entering  into  the  manufacture  of  Glass  from  a 
commercial  standpoint,  and  which  confront  the  glass  maker  each 
hour  and  day.  I  have  many  times  discussed  the  subject  of  Glass- 

57 


58  Original  Communications:  Eighth  International       [VOL. 

making  with  our  various  College  Professors  and  Deans  of  depart- 
ments, and  to  my  question,  "  Why  do  you  not  make  more  of  a 
study  of  glass?"  the  invariable  reply  is  made:  "  Because  of  the 
lack  of  problems  in  it  " — a  conclusion  which  they  have  arrived  at, 
no  doubt,  by  reason  of  the  non-progressiveness  of  the  majority 
of  our  glassmakers  and  manufacturers.  However,  to-day  the 
Glass  industry  is  assuming  a  far  different  attitude  and  position 
from  that  of  a  few  years  ago,  brought  about  by  the  advent  of 
machines  and  mechanical  manipulation  of  glass,  and  the  release 
of  the  industry  from  the  bondage  of  Unionism,  which  so  com- 
pletely held  it  in  its  grip  and  throttled  its  progressiveness  for 
centuries. 

Competition  has  become  so  keen  that  at  the  present  time  the 
manufacturer  must  look  to  economies  in  order  that  he  may  be 
able  to  "  make  ends  meet,"  to  say  nothing  of  declaring  dividends, 
and  whilst  some  are  still  content  to  conduct  their  business  accord- 
ing to  the  old  rules  and  custom,  nevertheless  there  are  a  few  who 
are  beginning  to  realize  that  the  chemist  and  industrial  engineer 
have  got  a  place  in  their  business,  and  that  the  successful  filling 
of  that  place  means  the  success  or  failure  of  their  enterprise. 

I  regret  very  much  that  I  am  unable  to  present  to  you  in  this 
paper  that  which  I  had  intended  when  I  assigned  its  title,  but, 
owing  to  illness,  I  have  been  unable  to  complete  many  experi- 
ments and  investigations  anticipated — and  started — at  the  time 
I  undertook  the  preparation  of  this  article,  and,  therefore,  I 
shall  have  to  be  content  in  here  presenting  such  data  as  I  have 
collected  as  bearing  upon  several  of  the  very  vital  problems,  the 
solution  of  which  would  place  in  the  Glass  manufacturer's  hands 
means  and  methods,  the  application  of  which  would  make  for  him 
a  handsome  dividend  each  year. 

Much  time,  money  and  energy  have  been  expended  in  designing, 
experimenting  with  and  perfecting  various  mechanical  devices 
for  the  cheapening  of  production,  by  eliminating  labor,  or  reduc- 
ing the  degree  of  skill  necessary  to  produce  the  finished  product. 
However,  still  there  followed,  and  there  was  always  present,  the 
uncertain  factor  of  quantity  of  production  controlled  by  the 
amount  of  good  ware  produced  and  that  quantity  of  glass  which 
it  was  necessary  to  melt  to  obtain  such  quantity  of  saleable  prod- 


v]  Congress   of  Applied  Chemistry  59 

uct,  the  difference  usually  being  accounted  for,  in  part,  by 
breakage  and  imperfections,  the  one,  in  many  instances,  being 
identical  with  the  other,  that  is  to  say,  the  cause  of  certain  imper- 
fections is  likewise  the  cause  of  breakage. 

The  manufacture  of  Window  Glass  by  the  various  mechanical 
processes,  suffers  particularly  from  breakage  losses,  and  it  was  in 
the  investigation  of  these  losses,  and  their  causes,  that  revealed 
some  quite  remarkable  conditions,  or  at  least  they  appeared  quite 
remarkable  at  the  time,  being  directly  contrary  to  the  accepted 
theories  and  beliefs  held  among  tradesmen  and  operators.  The 
experiments  and  results  hereafter  cited,  were  carried  on,  with 
the  exception  of  a  few  instances,  with  glass  that  was  made  by  the 
mechanical  process  of  drawing  glass  cylinders  from  a  bath  of 
molten  glass,  the  glass  being  a  soda-lime-silicate,  the  batch  form- 
ula of  which  consisted  of: 

Sand  1,000  Ibs. 

Crushed  Lime  Stone  330  Ibs. 

Salt  Cake  380  Ibs. 

Ground  Coal  18  Ibs. 

and  produced  what  was  known  to  the  trade  as  a  salt-cake  "  nor- 
mal "  glass.  The  glass  was  melted  in  a  tank  furnace,  the  dimen- 
sions of  which  were  approximately  18  ft.  inside  x  80  ft.  long,  and 
a  depth  of  glass  of  5  ft.  The  fuel  used  was  natural  gas,  which 
was  applied  in  a  method  similar  to  the  Siemens'  regenerative  proc- 
ess. On  each  side  of  the  furnace  there  were  five  ports  arising  from 
the  regenerative  chamber  through  which  the  air  passed,  being 
heated  by  the  retained  heat  of  the  checker  work  in  this  chamber, 
and  as  the  air  entered  the  furnace  the  gas  was  applied  and  mixed 
just  inside  the  furnace  wall,  passing  across  the  furnace  and  out  of 
the  ports  of  the  same  construction  on  the  other  side,  the  direction 
of  flow  of  gas  and  air  being  reversed  every  20  minutes,  in  the  usual 
well  known  manner.  The  furnace  temperature  at  the  melting  end 
was  maintained,  as  uniformly  as  possible,  at  about  1500  deg.  C. 
while  at  the  ladling,  or  working  end,  a  temperature  was  main- 
tained at  from  1100  to  1150  deg.  C. 

At  the  inauguration  of  the  mechanical  process,  the  glass  was 
melted,  and  the  furnace  operation  was  conducted  in  the  same 


60  Original  Communications:  Eighth  International       [VOL. 

manner  as  when  cylinders  were  made  by  the  hand  method.  It 
was  found,  however,  that  considerable  breakage  occurred,  which 
was  characterized  as  "  breaking  off  the  pipe  " — "  breaking  on  the 
horse  " — and  "  breaking  in  the  flattening  oven  " — meaning  in 
the  first  instance  that  the  glass  would  break  where  it  was  attached 
to  the  blow-pipe,  or  bait,  to  which  the  glass  adhered,  and  by 
means  of  which  it  was  withdrawn  in  cylinder  form,  from  the  bath 
of  molten  glass.  In  the  second  instance  there  were  two  forms  of 
breakage,  one  being  apparently  from  no  cause,  and  which  occurred 
shortly  after  the  cylinder  was  taken  down  and  laid  upon  horizont- 
al supports  called  the  "  horse,"  these  supports  consisting  of 
blocks  of  wood  held  in  metal  pieces  and  supported  by  springs. 

As  stated,  shortly  after  the  roller  was  placed  upon  these  sup- 
ports, without  any  warning,  and  apparently  from  no  cause,  it 
would  suddenly  seem  to  explode  and  would  break  in  thousands 
of  pieces  from  one  end  to  the  other  of  the  20-ft.  length. 

Another  form  of  "  breakage  on  the  horse  "  was  that  which 
occurred  when  the  operator  had  separated  the  roller  into  its 
respective  flattening  lengths,  it  being  necessary  to  make  from  6 
to  8  "  cuts  " — this  being  done  by  passing  a  wire  around  the 
cylinder,  electrically  heating  the  wire,  and  heating  the  cylinder 
along  a  line  of  narrow  dimensions,  applying  to  this  line  a  cold  or 
moistened  iron,  which  caused  a  sudden  contraction  and  fracture 
of  the  cylinder,  usually  along  the  line.  However,  many  times 
this  would  not  be  the  case,  and  instead  of  the  fracture  following 
the  narrow  heated  area,  it  would  depart  from  this  path,  and 
perhaps  run  in  "  cork-screw "  fashion  throughout  the  whole 
15  or  20-ft.  length.  Again  at  times  the  fracture  would  perhaps 
branch  off  at  a  tangent,  and  produce  a  rupture  of  all  manner  of 
fantastic  designs,  at  times  going  forward  for  a  distance  of  a  few 
feet  or  more,  perhaps  returning  in  a  circle  of  6  to  12  inch  radius, 
reverse  its  direction  and,  in  a  smaller  circle,  start  out  and  encircle 
the  roller,  or  progress  along  its  length.  At  other  times  the  frac- 
ture, under  these  conditions,  would  assume  a  straight  line,  or 
perhaps  a  spiral  line  along  the  length  of  the  cylinder. 

The  breakage  during  the  first  six  or  eight  months  of  operation 
by  mechanical  process  would  average  70%,  and  at  short  intervals 
go  as  high  as  95%.  After  a  time  of  experimenting  it  was  decided 


v]  Congress  of  Applied  Chemistry  61 

to  change  the  batch  mixture,  supplanting  the  major  portion  of 
the  salt  cake  with  soda  ash,  and  finally  it  was  found  that  with  a 
batch  consisting  of: 

Sand  1,000  Ibs. 

Crushed  Lime  Stone  328  Ibs. 

Soda  Ash  (58%)  240  Ibs. 

Salt  Cake  80  Ibs. 

the  breakage  was  very  materially  reduced,  also  that  many  of  the 
imperfections,  more  particularly  those  known  as  "  cords  "  and 
"  strings/'  were  reduced,  these  being  narrow  areas  where  the  glass 
was  somewhat  thicker  in  section,  usually  being  caused  by  there 
being  a  local  area,  in  the  mass  of  glass  from  which  the  cylinder 
was  drawn,  which  had  suffered  a  reduction  in  temperature,  or 
being  due  to  a  lack  of  chemical  homogenity  in  the  metal.  How- 
ever, a  great  deal  of  breakage  occurred,  and  it  was  found  that  it 
was  very  ununiform,  being  perhaps  40  per  cent,  one  day  and  the 
next  day  jumping  to  50  or  60  per  cent.  It  was  also  found  that  the 
breakage  in  the  flattening  oven  would  increase  at  times  when  the 
breakage  on  the  machine  was  at  its  lowest. 

These  conditions  were  all  very  puzzling,  and  up  to  that  time 
there  seemed  to  be  no  literature  on  the  subject  of  "  Glass  " 
which  would  give  any  definite  accounting,  even  in  a  general  way, 
or  any  specific  cause  for  the  breakage  occurring.  A  careful  study 
had  been  made  of  all  the  furnace  conditions,  taking  into  account 
the  amount  and  composition  of  material  charged  into  the  furnace, 
the  gas  and  air  consumed,  draft  conditions,  waste  gas  analyses, 
temperature,  etc.  To  a  degree,  variations  in  these  conditions 
coincided  with  the  breakage,  yet  no  one  variable  condition  did  so 
with  sufficient  definiteness  whereby  it  could  be  accredited  with 
having  been  the  cause  of  any  particular  form  of  breakage. 

There  would  also  occur  at  times,  a  breakage  of  from  15  to  20 
per  cent,  in  the  flattening  oven,  the  primary  cause  being  the 
checking  or  shrending  of  the  surface  of  the  cylinder  by  the  elec- 
trically heated  wire  causing  a  too  high  local  temperature,  which 
would  shrend  or  check  the  outside  surface  to  a  depth  of  perhaps 
.001  inch,  or  in  some  instances  .013  or  .014  of  an  inch.  However, 
this  same  checking  might  occur  at  intervals  and  produce  no 


62  Original  Communications:  Eighth  International       [VOL. 

breakage  in  the  oven,  and  again  the  same  temperature  of  wire, 
under  the  same  manipulation,  would  not  produce  this  checking, 
all  of  which  appeared  to  be  problems  governed  by  the  properties 
of  the  glass.  The  explosive  nature  noted  in  "  breaking  on  the 
horse  "  would  also  be  noted  in  the  flattening  oven,  where,  in  per- 
haps 40  to  60  seconds  after  the  split  cylinder  was  "  shoved  in," 
and  was  resting  under  the  shade  stone,  it  would  suddenly  become 
disrupted  and  break  in  thousands  of  pieces. 

These  same  conditions  are  not  only  noted  in  the  production  of 
window  glass,  but  may  also  be  seen,  in  modified  forms,  in  the 
manufacture  of  plate  glass,  tumblers,  lamp  chimneys,  pressed 
ware  of  all  description,  and  even  in  cut  glass.  A  particular 
instance  which  has  come  to  my  notice,  and  which  has  revealed 
some  quite  unusual  and  aggravating  conditions,  is  that  of  the 
manufacture  of  sidewalk  glass.  I  have  more  specific  data  on 
window  glass,  and  will  confine  myself  to  presenting  this  data, 
which  may  be  used  and  applied  where  conditions  are  analogous 
in  other  branches  of  the  art. 

Examinations  of  specimens  of  glass  cut  from  cylinders  which 
exploded  on  the  horse,  or  from  sample  pieces  taken  from  such 
cylinders,  immediately  after  having  come  from  the  machine  which 
formed  same,  or  from  the  workman's  hands  who  made  the  article, 
revealed  excessive  strains  existing  on  the  exterior,  as  also  consid- 
erable strains  on  the  interior  surfaces  of  the  cylinders.  It  was 
determined  that  they  were  compression  strains  which  penetrated 
the  glass  to  about  12  per  cent,  of  its  thickness  on  the  outside,  and 
8  per  cent,  on  the  inside,  but  which  in  some  instances  would  be 
as  great  as  25  per  cent,  on  the  outside  and  not  over  3  or  4  per 
cent,  on  the  inside.  This  determination  was  made  by  ascertain- 
ing the  double  refraction.  This  consisted  of  cutting  from  a  cylin- 
der (by  means  of  a  diamond  or  wheel)  specimens  ^  inch  wide, 
placing  them  on  edge  in  a  holder,  or  substage  of  a  Petrographic 
Microscope,  at  45  deg.  to  the  plane  of  the  Nicols.  By  introducing 
a  quartz  wedge  to  give  a  phase  difference  as  to  produce  red  of  the 
first  order,  or  a  selenite  plate,  so  that  their  c  direction  was  at 
right  angle  to  the  plane  of  the  specimen,  and  on  then  viewing  the 
specimen  with  the  1-inch  ocular  and  1  J-inch  objective,  and  using 
crossed  nicols,  it  was  found  that  the  orientation  of  the  strained 


v]  Congress   of  Applied  Chemistry  63 

portion  of  the  specimen  was  distinct  and  well  denned,  and  pro- 
duced a  bright  yellow  color,  denoting  a  crushing  strain. 

This  was  contrary  to  the  belief  of  practical  men,  who  held 
that  the  outside  and  inside  surfaces  were  under  tension,  the  fact 
being,  however,  that  when  the  cylinder  walls  are  formed  and 
withdrawn  from  the  surface  of  the  bath  of  semi-molten  metal,  its 
dimensions  are  formed  and  fixed  by  the  solidifying  of  the  exterior 
and  interior  surfaces,  while  the  interior  section  of  the  sheet,  or 
cylinder,  is  yet  in  a  mobile,  or  plastic  state,  which  later  cools  and 
contracts  upon  the  already  solid  and  fixed  exterior  and  interior 
surfaces,  thereby  producing  a  compression  upon  these  surfaces, 
and  a  tension  upon  the  interior  of  the  section,  whose  orientation 
produces  wave  lengths  the  path  difference  of  which  ranges  from 
.001  to  .004,  and  in  extreme  cases  .OOGft/A,  this  being  more 
clearly  differentiated  by  the  introduction  of  the  selenite  plate,  or 
a  quartz  wedge,  in  order  to  get  a  phase  difference,  or  retardation 
of  the  light  rays  of  about  525  to  550  /x/x,  and  which,  as  stated 
above,  determines  the  orientation,  that  is,  determines  whether 
the  specimen  under  examination  be  under  compression  or  ten- 
sion, and  to  some  extent  the  degree  of  such  strain  if  the  thickness 
of  the  specimen  be  known.  This  has  been  positively  proven,  and 
in  fact  by  the  use  of  a  special  Fedorow  wedge,  designed  and  com- 
puted by  Fred  Eugene  Wright  of  the  Carnegie  Geophysical 
Laboratory,  it  is  possible  to  calibrate  the  exact  amount  of  strain 
introduced  in  pounds  per  square  inch,  or  grams  per  square 
centimeter. 

By  use  of  the  Wright  wedge,  or  compensator,  it  has  been  very 
easy  to  demonstrate  the  enormous  strains  which  have  been  intro- 
duced by  reason  of  the  chemico-heterogeneity,  as  also  those 
strains  caused  by  cooling,  or  unequal  solidification  and  contrac- 
tion during  the  formation  of  the  article.  It  is  found  that  the  com- 
pression strains  on  the  exterior  of  the  cylinder,  may,  at 
times,  reach  the  enormous  pressure  of  90,000  Ibs.  per  square  inch. 
However,  it  seems  that  these  pressures  are  not  so  directly  re- 
sponsible for  breakage  as  are  the  strains  introduced  by,  what  I 
have  termed,  a  physical  heterogeneity,  meaning  by  the  term  an 
introduction,  into  a  sheet  or  article  of  glass,  of  a  local  or  narrow 
area  of  metal  which  has  been  cooled  and  solidified  previous  to 


64  Original  Communications:  Eighth  International       [VOL. 

the  solidification  of  the  balance,  or  major  portions  of  the  article. 
Further,  when  the  compression  strains  occur  by  reason  of  the 
formation  of  the  article,  as  above  explained,  and  the  mass  is  not 
homogeneous  in  its  composition,  small  portions  or  areas  being  of  a 
greater  or  less  density,  this  immediately  creates  a  path  or  line  of 
least  resistance,  through  which  fracture  will  occur  should  there 
be  any  occasion  whatsoever  for  these  conflicting  strains  to  exert 
themselves,  as  in  separating  the  cylinder  with  the  hot  wire,  or 
sudden  cooling  of  the  surface  of  the  glass,  introducing  additional 
crushing  strain  at  or  near  the  junction  of  this  strain,  which  then 
sets  up  either  chemical  or  physical  heterogeneity,  in  which  event 
a  complete  disruption  of  the  article  will  usually  occur,  or  should 
the  chemical  differences  in  composition  lie  in  definite  lines  of  cork- 
screw fashion  throughout  the  length  of  the  cylinder,  this  would  be 
the  path  of  the  fracture,  as  cited.  Should  it  be  so  disseminated  as 
to  form  a  considerable  portion  of  the  mass  comprising  the  cylinder 
or  article,  it  will  then  have  the  explosive  effect;  or  should  the 
exterior  have  suffered  sufficiently  rapid  reduction  in  temperature 
over  that  of  the  interior,  there  is  a  tendency  to  produce  this 
explosive  effect,  although  in  the  latter  conditions  the  edges  of  the 
fractures  will  have  a  shivered  appearance,  denoting  a  tendency 
to  separate  the  article  through  its  longitudinal  section,  producing 
some  sharp  edges. 

It  has  been  stated  that  this  breakage  has  been  produced  pri- 
marily by  conflicting  strains  set  up  by  tension  and  compression 
due  to  physical  and  chemical  heterogeneity.  This  was  determined 
by  two  methods,  one  being  by  etching  the  glass  with  HF,  and 
making  an  analysis  of  that  portion  dissolved,  in  the  following 
manner: 

A  specimen  of  the  glass  was  cut  to  a  size  sufficient  to  cover  a 
platinum  dish  about  ij  inches  in  diameter,  the  specimen  being 
about  2  inches  in  diameter,  if  possible.  They  were  washed  and 
made  perfectly  clean,  rinsed  with  alcohol  and  ether,  dried  and 
weighed.  There  was  placed  in  the  dish  10  cc.  of  HF,  which  was 
then  covered  with  the  specimen,  subjected  to  a  temperature  of 
water  bath  (about  90  deg.  C.)  until  all  of  the  acid  had  been  volat- 
ilized and  had  acted  upon  this  specimen,  after  which  it  was 
boiled  in  HC1  and  washed  perfectly  free  from  any  adhering  resi- 


Fig.  I. 


Fig.  II. 


Fig.  III. 


Fig.  IV. 


Fig.  V. 


Fig.VI. 


Fig.  VII. 


v]  Congress  of  Applied  Chemistry  65 

due.  H2S04  was  then  added,  evaporated  to  dryness,  and  sub- 
jected to  low  red  heat  to  expell  all  the  silicon  fluoride,  analysis 
then  being  made  of  that  portion  dissolved  from  the  glass.  The 
specimen  was  then  again  washed  with  alcohol  and  ether,  and 
weighed  so  as  to  determine  the  amount  dissolved  by  the  HF. 

It  was  found  that  the  portions  affected  by  HF,  when  examined 
by  the  microscope  and  polarized  light,  showed  striae,  and  which, 
as  usually  was  the  case,  showed  that  the  heavy  cord,  or  ream, 
would  suffer  more  or  less  from  the  effect  of  the  HF,  depending 
upon  whether  same  contained  a  greater  or  less  amount  of  lime 
silicates  than  was  present  in  the  surrounding  clear  glass.  Fur- 
ther, if  this  etched  portion  be  closely  examined  by  higher  magnifi- 
cation, there  would  be  distinguished  areas  of  ununiform  solubility, 
and  many  times  well  defined  crystals,  or  the  outlines  of  such 
crystals  in  the  matrix  of  higher  or  lower  silicates  in  which  they  had 
resided.  There  also  appeared  to  be  a  considerable  difference  in 
the  appearance  of  the  etched  portion  of  various  samples,  some 
having  a  very  close  granular  structure,  as  is  shown  in  the  accom- 
panying Fig.  1,  and  others  having  a  nodular  appearance,  of  1  or 
2  mm  in  diameter,  as  is  shown  in  Figs.  2  and  3,  although  such 
structures  were  not  perfectly  round. 

Fig.  4  illustrates  what  seems  as  an  impossible  narrow  area  of 
chemical  heterogeneity.  As  is  seen  in  the  center  of  the  photo- 
graph, the  acid  etched  the  glass  to  a  considerable  depth,  and  a 
similar  area  near  to  the  margin.  In  this  specimen  it  was  found 
that  the  Soda  ran  abnormally  high  in  the  analysis  of  the  etching 
residue. 

Fig.  5  is  an  illustration  of  an  etching  wherein  the  acid  has  dis- 
solved the  crystals  from  the  matrix  in  which  they  lay,  and  in  this 
analysis  the  Silica  was  high.  Under  conditions  as  shown  in  Fig. 
5,  where  there  appeared  to  be  crystalline  compounds,  which, 
although  perfectly  transparent  to  the  eye,  with  the  aid  of  the 
microscope  showed  an  unusual  thickness  or  layer  of  compression 
strain  on  the  exterior  of  the  cylinder,  and  the  breakage  in  this 
instance  was  very  great,  while  under  conditions  as  shown  in  Fig. 
3,  the  breakage  would  amount  to  from  7  to  12  per  cent,  it  being 
exceptionally  low. 
5 


66  Original  Communications:  Eighth  International       [VOL. 

In  viewing  a  specimen  cut  in  transverse  section,  or  in  looking 
at  the  edge  of  a  cylinder  lengthwise,  in  cases  of  poor  melting,  or 
chemical  heterogeneity,  a  striated  condition  would  be  very  pro- 
*  Fi.  6  showinc- 


Fig.  7  is  a  good  example  of  a  well  made  glass,  and  one  in  which 
the  breakage  was  very  low.  As  will  be  seen,  the  outside  shows  a 
strain  somewhat  heavier  than  the  inside,  but  the  specimen  is 
perfectly  free  from  striae. 

The  photo-micrographs,  Figs.  6  and  7,  were  taken  with  crossed 
nicols,  but  with  no  selenite  plate  intervening.  Fig.  7  is  under 
lower  magnification  than  are  the  other  illustrations,  it  being 
about  20  diameters  while  the  others  are  magnified  to  80  diameters. 

While  the  method  above  referred  to  gives  us  specific  and  defi- 
nite information  as  to  the  lack  of  chemical  homogeneity  of  the 
glass,  nevertheless  same  is  subject  to  more  or  less  inaccuracies, 
and  there  arise  many  conditions  in  composition  which  are  more  or 
less  confusing,  particularly  as  to  just  what  element  the  cord  or 
disrupting  cause  is  due  to.  Therefore  I  have  sought  for  other 
methods  and  means,  which  do  not  require  skill  and  time  to  deter- 
mine these  chemical  changes  and  variables,  that  may  be  applied 
with  definiteness  and  at  the  same  time  enable  one  to  apply  the 
results  in  operating  the  furnace  and  in  controlling  the  batch  mix- 
ture, and  I  believe  that  the  determination  of  the  refractive  indices 
of  the  glasses,  offers  a  solution  of  the  problem. 

As  has  recently  been  stated  by  Tillotson,  it  is  quite  possible  to, 
within  certain  limits,  affix  a  specific  refractive  index  for  each  of  the 
ingredients  used  in  the  making  of  commercial  glass,  and  such 
being  the  case  it  seems  that  it  would  be  quite  possible,  by  a  sys- 
tem or  a  series  of  analyses  and  refractive  indices  determination 
of  the  various  combinations  of  silicate  of  lime  and  soda,  to  acquire 
information  of  sufficient  accuracy  as  to  denote  the  exact  cause  of 
this  heterogeneity,  and  while  it  is  of  course  true  that  fire  condi- 
tions may  bring  about  sufficient  disturbing  influence  upon  the 
melting  glass  as  to  be  the  cause  of  breakage,  yet  I  believe  that 
this  reveals  itself  in  disturbing  the  refractive  index  to  a  much 
less  degree,  if  at  all,  and  that  one  will  be  enabled  to  differentiate 
this  condition  from  improper  chemical  combinations. 


v]  Congress  of  Applied  Chemistry  67 

It  was  this  part  of  my  investigations  that  I  was  unable  to  com- 
plete. However,  I  have  made  a  number  of  determinations  of  the 
refractive  indices  of  glasses  as  they  came  from  the  furnace,  and 
have  compared  such  determinations  with  the  analyses,  etchings 
and  microscopic  examinations,  as  above  referred  to,  and  find  that 
they  are  much  more  accurate  and  definite  in  their  definition  as  to 
the  cause  of  breakage,  although  perhaps  not  quite  so  specific  as 
to  the  elementary  cause,  that  is  to  say,  one  can  very  easily  deter- 
mine whether  the  breakage  is  due  to  chemical  heterogeneity, 
physical  heterogeneity,  or  to  excessive  strain  produced  by  too 
rapid  cooling,  as  is  shown  by  the  following  instances: 

The  method  used  was  as  follows — samples  were  taken  from  the 
cylinders,  or  articles,  as  they  came  from  the  machines  or  work- 
men, crushed  by  tapping  in  an  agate  mortar  so  that  the  major 
portion  would  pass  a  60  sieve.  The  refractive  index  of  the  speci- 
mens was  determined  by  the  Becke  line  method,  using  a  Bausch 
&  Lomb  Petrographic  Microscope,  applying  the  1  inch  ocular  and 
8  mm  and  4  mm  objectives.  A  series  of  oils  of  different  composi- 
tions were  compounded,  the  refractive  index  of  same  being  varied 
by  2  points  in  the  third  decimal  place,  I  using  for  the  major  por- 
tion Oil  of  Juniper  (n  =  1.4761),  Oil  of  Sassafras  (n  =  1.5233) 
and  Oil  of  Cinnamon  (n  =  1.5773),  and  making  mixtures  of  these 
compound  oils  as  requirements  demanded  to  get  the  proper 
index  to  the  fourth  or  fifth  decimal  place.  The  instrument  used 
was  a  Fuess,  Model  II,  Refractometer.  It  was  found  that  one 
could  easily  determine  the  indices  to  the  fourth  or  fifth  decimal, 
although  no  attempt  was  made,  with  the  exception  of  peculiar 
cases,  to  reach  this  degree  of  accuracy.  To  illustrate  the  possi- 
bilities of  this  method,  one  or  two  instances  will  suffice. 

A  sample  of  glass  which  was  taken  at  the  time  when  breakage 
was  very  heavy,  and  in  which  several  heavy  cords  were  seen  in 
each  cylinder,  showed  a  refractive  index  of  the  clear  glass  (Speci- 
men C-251)  of  1.5253,  while  the  cord  (Specimen  C-252)  indicated 
1.5088. 

In  another  instance,  where  the  tank  had  been  running  very 
badly,  the  gas  being  low  and  the  fire  being  very  poor,  much  diffi- 
culty had  been  experienced  in  melting  sufficient  batch  to  keep 
the  glass  at  the  proper  level,  and  much  trouble  experienced  from 


68  Original  Communications:  Eighth  International        [VOL. 

cords  being  produced  by  reason  of  the  cold  air  blowing  into  the 
gathering  holes,  and  which  produced  what  is  known  as  the  "  cold 
cord."  In  this  sample  it  was  found  that  the  thickness  of  the 
clear  glass  was  .145  inch,  while  the  chemical  cord  was  .157  inch 
thick,  and  the  cold  cord  about  .15  inch  thick.  The  natural  glass 
(Specimen  C-253)  had  a  refractive  index  of  1.522.  The  chemical 
cord  (Specimen  C-254),  in  which  there  were  seen  small  nodes,  or 
thickened  portions  of  about  .1  inch  or  2.5  mm  in  diameter,  had 
an  index  of  1.519.  Specimens  of  the  physical  cord  (C-255),  which 
were  trimmed  as  free  from  the  surrounding  glass  as  possible,  gave 
an  index  of  1.521,  and  there  also  appeared  several  crystals,  more 
or  less  anisotropic,  having  an  index  of  1.517. 

Many  times  in  the  crushing  of  glass  it  is  noted  that  there 
appear  to  be  portions  that  are  more  friable,  or  brittle,  than  are 
others,  and  in  one  sample  where  this  appeared  to  be  quite  marked, 
it  was  found  that  the  main  portion  of  the  part  investigated, 
same  being  a  chemical  cord  (Specimen  C-257)  gave  an  index  of 
1.518,  while  that  for  the  hard,  or  unfriable  portion,  was  1.522, 
and  which  corresponds  with  the  index  of  the  clear  glass  surround- 
ing the  cord.  In  making  determinations  of  several  other  speci- 
mens of  Chemical  Cord  C-257,  concordant  results  were  obtained 
with  those  denoted,  the  indices  remaining  at  1.518  and  1.519. 

In  specimen  C-258,  being  glass  from  the  same  tank,  the 
batch  composition  being  identical,  and  the  conditions  throughout 
being  as  near  the  same  as  could  be  expected,  in  commercial  opera- 
tion, as  when  C-251  was  taken,  but  being  from  a  several  months' 
later  production,  I  obtained  an  index  for  the  clear  glass  of  1.52, 
while  the  cord  in  this  case  (Specimen  C-259)  gave  an  index  of 
1.5237,  this,  as  will  be  noted,  being  directly  opposite  to  the  con- 
ditions as  found  in  C-253,  C-254  and  C-255. 

Several  months  after  the  above  mentioned  specimens  were 
taken,  the  glass  from  this  furnace  showed  an  index  of  1.524, 
and  which  was  no  doubt  due  to  a  reduction  in  Soda,  the  Salt 
Cake  in  the  batch  analysis  showing  that  the  Soda  content  was 
nearly  1  per  cent,  lower,  and  the  Silica  content  nearly  .6  per  cent, 
higher  than  heretofore. 

In  the  making  of  lenses  there  is  often  considerable  difficulty 
experienced  in  producing  the  blanks  free  from  reams  or  striae, 


v]  Congress  of  Applied  Chemistry  69 

and  it  has  been  quite  a  problem,  and  a  matter  of  much  conjecture 
among  the  manufacturers,  as  to  what  is  the  due  cause — whether 
it  be  from  erosion  of  the  pots,  or  due  to  the  chilling  of  the  glass 
during  the  process  of  melting — and  it  would  seem  that  the  results 
found  in  my  experiments  would  answer  this  question  quite  deci- 
sively, inasmuch  as  that  portion  of  the  lens  which  was  clear  gave 
an  index  of  1.512,  while  the  portion  which  showed  striae  gave 
1.5136. 

In  the  manufacture  of  bottles,  lamp  chimneys,  globes,  table 
ware,  and  particularly  lantern  lenses,  automobile  reflectors, 
semaphores,  tumblers,  or  other  articles  which  are  required  to 
stand  variables  temperatures,  the  question  of  breakage  is  a  very 
vital  one,  and  should  it  be  possible  to  work  out  a  complete  and 
definite  method  as  simple  as  is  the  determination  of  the  refractive 
indices,  as  above  outlined,  it  would  be  something  which  would  be 
accepted  and  hailed  with  delight  by  every  progressive  manufac- 
turer in  the  country.  He  knows,  of  course,  that  his  ware  is  break- 
ing either  because  of  injudicious  handling  or  because  of  improper 
making,  but  rarely,  if  ever,  does  he  know,  and  in  fact  it  is  quite 
difficult  to  convince  him  that  this  breakage  is  due  to  the  mix- 
ing, melting,  or  control  of  the  conditions  surrounding  the  han- 
dling of  his  glass  prior  to  the  time  that  it  reaches  the  solid  state, 
and  it  would  be  of  inestimable  value  and  benefit  if  our  industrial 
scientists  could  place  in  his  hands  some  simple,  non-scientific 
but  practical  method  and  means  whereby  he  could  with  certainty 
and  definiteness  control  his  operations  and  obtain  uniform  results. 

The  Glass  industry  is  undergoing  radical  and  revolutionary 
improvements,  much  money  and  time  being  spent  in  experi- 
menting with  and  developing  these  improvements,  relying  upon 
protection  of  Patents  so  as  to  give  sufficient  monopoly  to  warrant 
the  vast  expenditures  necessary  to  demonstrate  the  practicability 
of  such  inventions  and  improvements.  However,  a  little  investi- 
gation of  the  Patents  issued  in  the  United  States,  and  the  basis 
for  the  claims  in  such  Patents,  will  soon  reveal  the  fact  that  there 
is  substantially  no  understanding  of  the  laws  and  principles  gov- 
erning the  properties  of  glass,  nor  of  the  chemical  actions  and 
reactions  controlling  its  composition,  and  among  some  of  the  more 
educated  capitalists  controlling  certain  branches  of  the  industry, 


70  Original  Communications:  Eighth  International       [VOL. 

this  has  come  to  be  a  serious  consideration  in  the  point  of  further 
investment  towards  getting  improvements,  for,  unfortunately, 
we  Americans  are  prone  to  shun  investment  unless  large  returns 
are  in  sight,  and,  unlike  our  foreign  relations  and  associates, 
we  do  not  depend  upon  our  research  laboratories  and  competent 
and  loyal  help,  to  carry  out  the  more  salient  and  less  obvious 
factors  in  our  manufacturing  processes  rather  than  relying  upon 
published  facts  and  theories,  protected  by  Patents,  law  and  juris- 
diction. 

I  have  been  connected  with  the  Glass  industry  in  its  various 
branches,  from  the  point  of  employee,  operator  and  inventor, 
and  in  the  research  laboratory,  and  have  also  been  more  or  less  in 
intimate  touch  with  other  industries,  and  in  my  opinion,  without 
doubt,  the  Glass  industry  is  the  most  neglected,  but  has  more 
intricate  problems  than  any  other  that  has  come  to  my  attention, 
and  its  problems  are  difficult  ones  by  reason  of  the  fact  that  but 
few  of  them  manifest  themselves  by  the  production  of  a  direct 
result,  but  in  the  majority  of  cases  are  hidden,  or  conceal  them- 
selves, by  reason  of  the  very  transparency  of  the  material. 

I  earnestly  hope  that  our  scientists,  industrial  engineers,  pro- 
fessors, and  students,  will  take  a  greater  and  a  deeper  interest 
in  the  problems  confronting  the  manufacturer,  and  I  shall  cer- 
tainly be  very  pleased  to  devote  my  time  and  laboratory,  and  give 
personal  escort  to  those  sufficiently  interested,  to  the  plants 
with  which  I  am  connected,  for  I  feel  that  it  is  only  in  the  prac- 
tical operating  plant  that  these  problems  manifest  themselves, 
and  where  real  and  beneficial  results  can  be  accomplished  which 
can  be  made  to  produce  profits  and  dividends,  and  without  such  a 
final  conclusion  to  the  work,  very  little,  if  any,  progress  will  be 
made  in  getting  at  the  more  concrete  factors  of  this  industry, 
for  it  is  doubtful  if  there  is  any  University,  educational  institu- 
tion, or  private  individual  who  would  feel  like  spending  a  sum 
sufficient  to  erect  and  operate  furnaces  for  experimental  research 
purposes,  of  dimensions  that  would  produce  the  conditions  found 
in  practical  operating  plants. 

With  the  assistance  of  the  manufacturers  and  capitalists  who 
are  operating  the  plants  for  a  profit,  and  with  the  aid  of  judicious 
scientific  investigation,  which  they  can  be  shown  will  produce 


v]  Congress  of  Applied  Chemistry  71 

added  profit,  it  seems  that  it  is  possible,  by  proper  investigation 
and  research,  to  produce  glasses,  and  the  apparatus  for  manip- 
ulating the  same,  as  to  greatly  broaden  the  field  of  its  use,  either 
by  improving  its  properties  in  the  way  of  resistance  to  fracture 
and  heat,  or  reducing  the  losses,  for  it  is  true  that  it  is  the  cheapest 
commercial  commodity  in  the  crude  state  of  any  of  our  building 
materials.  Is  it  not  possible  that  we  may  step  from  fancy  and 
fiction  into  fact  and  reality,  and  build  our  houses  of  glass,  conduct 
our  water  supplies  through  glass,  and  sanitate  and  insulate  in  a 
manner  that  would  be  of  great  universal  benefit? 


MAGNESIA  IN  PORTLAND  CEMENT 


BY  A.  A.  KLEIN  AND  A.  J.  PHILLIPS 
Bureau  of  Standards,  Pittsburg,  Pa. 

In  the  testing  of  cements  by  this  laboratory  a  number  were 
found  which  were  rejected  on  account  of  their  high  MgO  content, 
the  limit  for  acceptance  having  been  placed  at  3%.  While  in 
some  cases  the  MgO  content  exceeded  7%,  a  study  of  the  physi- 
cal tests  revealed  little  cause  for  their  rejection,  a  few  having 
failed  in  the  boiling  test  but  on  ageing  and  retesting  the  pats 
were  satisfactory.  On  this  account  it  was  decided  to  study  more 
completely  a  number  of  picked  samples  with  increasing  MgO 
content  in  order  to  determine  how  the  MgO  was  combined,  and 
if  any  reason  could  be  found  for  making  a  sharp  rejection  at  3%. 
The  analysis  of  these  samples  are  given  in  Table  I.  A  petro- 

TABLE  I. 


1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

SiO2, 

21.38 

21.57 

21.06 

21.63 

22.58 

20.65 

20.94 

21.87 

21.92 

21.68 

21.47 

A1203, 

8.22 

9.07 

8.10 

7.55 

8.30 

6.52 

6.36 

7.09 

7.07 

6.97 

7.19 

Fe203, 

2.22 

2.36 

2.51 

2.65 

2.09 

2.36 

2.43 

2.34 

2.31 

2.29 

2.34 

CaO, 

62.29 

61.14 

62.44 

62.12 

60.92 

61.49 

61.92 

57.47 

57.46 

58.32 

57.94 

MgO, 

2.87 

3.09 

3.32 

3.53 

3.70 

4.55 

4.79 

6.02 

6.28 

6.55 

7.07 

S03, 

1.94 

1.38 

1.70 

1.65 

1.58 

1.58 

1.58 

2.05 

2.12 

1.78 

1.70 

Ig, 

.53 

.68 

.56 

.45 

.40 

1.85 

1.19 

2.24 

2.05 

1.68 

1.55 

graphic  examination,  using  the  methods  employed  by  the  Geo- 
physical Laboratory  in  their  investigation  of  the  ternary  system 
CaO-SiO^A^Os,1  showed  that  the  most  abundant  constituents 
present  were  the  B  2CaO.SiO2  and  3CaO.Al2O3  while  3CaO.Si02 
and  5Ca0.3Al2O3  were  present  only  in  small  quantities.  Con- 
trary to  the  theories  of  some  former  investigators,  neither  MgO 


'J.  Ind.  Eng.  Chem.  3,  221-27. 


73 


74  Original  Communications:  Eighth  International       [VOL. 

nor  MgO.Al203  were  found  present.  Monochramatic  Na  light 
was  used  in  their  investigation,  since  3CaO.Al2O3,  MgO  and  MgO. 
A12O3  are  all  isotropic  with  indices  of  refraction  very  close  to  one 
another.  There  was  observed  condiserable  CaC03  which  origin- 
ally must  have  been  present  as  free  CaO,  and  this  would  seem  to 
account  for  the  failure  of  a  few  of  the  cements  to  pass  the  acceler- 
ated tests.  That  this  compound  was  CaC03  and  not  MgC03  was 
definitely  ascertained  by  the  maximum  index  which  was  found 
to  be  about  1.66,  that  of  the  MgC03  being  1.717. 

The  cements  were  exceedingly  fine  grained,  the  largest  crystal- 
lites being  those  of  the  /32CaO.Si02  which  never  exceeded  0.03 
mm.  in  length  and  few  attained  that.  This  coupled  with  the 
fact  that  the  cements  when  received  for  examination  were  finely 
ground,  rendered  the  determination  of  the  optical  constants  and 
the  identification  of  the  constituents  a  very  difficult  and  pains- 
taking matter.  The  orthosilicate  and  tri-aluminate  agreed  very 
closely  with  those  described  by  Shepherd,  Rankin  and  Wright 
in  all  determinable  properties  except  the  index  of  refraction  which 
was  lower  in  both  instances  and  furthermore  was  not  constant. 
This  lowering  of  the  refractive  index  and  the  absence  of  MgO  and 
MgO.Al2O3  led^to  the  investigation  of  the  possibility  of  the  re- 
placement of  CaO  by  MgO  in  these  compounds. 

The  program  outlined  consisted  of  the  burning  and  microscop- 
ical examination  of  2CaO.SiO2  and  3CaO.Al203  in  which  the 
CaO  was  partly  replaced  by  MgO  according  to  molecular  pro- 
portion. Also  in  view  of  the  fact  that  in  the  cement  industry 
CaO  and  MgO  are  calculated  together,  a  small  series  of  burns 
were  made  in  which  definite  percentages  of  CaO  were  replaced 
by  MgO. 

The  materials  used  were  a  flint  containing  but  0.2%Pe203,  a 
light  calcined  MgO  containing  but  0.5%  Si02,  C.  P.  CaCO3  and 
Al  oxide  containing  no  Si02  or  CaO.  The  various  mixes  were 
moulded  into  small  hollow  cylinders  and  burned  in  a  pot  furnace, 
using  natural  gas  and  compressed  air,  the  samples  resting  on  a 
magnesite  base  which  offered  practically  no  contamination  at  the 
temperatures  employed.  The  effort  was  made  to  produce 
homogeneous  samples  with  satisfactory  crystal  growth  for  optical 
examination  at  temperatures  as  close  as  possible  to  rotary  kiln 


v]  Congress  of  Applied  Chemistry  75 

practice.  In  cases  where  homogeneity  was  not  satisfactory,  the 
samples  were  reground  and  reburned  several  times  until  satis- 
factory. The  burning  temperatures  in  no  case  exceeded  1500° 
and  the  time  varied. 

The  /32CaO.Si02  were  first  made  according  to  the  formula  2 
(mCaOnMgO)  Si02  in  which  m  and  n  were  varied  to  give  com- 
pounds ranging  from  2CaO.SiO2  to  CaO.MgO.SiO2. 

The  first  effect  noted  was  that  burning  2CaO.SiO2  at  tempera- 
ture not  exceeding  1500°  was  followed  by  dusting;  remoulding 
and  reburning  the  sample  several  times  had  no  preventive  effect 
on  the  dusting.  The  additions  of  MgO  in  increasing  amounts 
diminished  the  dusting.  Up  to  4%,  however,  it  was  necessary 
to  remould  and  reburn  the  specimens  to  produce  non-dusting 
samples.  With  increasing  MgO  the  clinker  became  harder  and 
more  vitreous,  the  softening  point  falling  so  that  a  sample  con- 
taining 15%  MgO  could  not  be  burned  with  a  5%  sample  for  the 
same  length  of  time  on  account  of  the  melting  of  the  former. 

The  microscopic  examination  of  CaO.MgO.SiO2  showed  it  to 
be  homogeneous  and  composed  of  crystallites  showing  a  prismatic 
development.  The  indices  of  refraction  were  determined  as 
f olio ws:L  =  1.649+ .003,  0  =  1.60+.003  and y  =  1.664+. 003, X-y 
being  0.016  approximately.  Occasional  cleavage  was  observed 
and  parallel  extinction  noted.  The  optical  character  was  nega- 
tive. These  properties  agree  closely  with  those  of  the  mineral 
Monticellite  (CaO.MgO.Si02)  of  the  Olivine  series. 

The  examination  of  the  dusted  specimens  revealed  y  orthosili- 
cate  with  occasionally  a  small  amount  of  ft.  It  was  determined 
that  MgO  does  not  form  a  homogeneous  product  with  CaO  to 
any  appreciable  extent  in  the  y  orthosilicate  because  of  the  pres- 
ence of  the  MgO  in  the  dust.  Reburning  of  the  dusted  specimens 
eliminated  the  dusting.  The  specimens  now  showed  an  absence 
of  y  orthosilicate  and  MgO  and  the  presence  of  ft  orthosilicate 
with  a  minimum  mean  refractive  index  of  about  1.70,  that  of  the 
pure  ft  2CaO.Si02  being  about  1.725.  This  homogeneity  was 
observed  in  specimens  containing  up  to  6%  MgO.  At  this  point 
traces  of  unhomogeneity  were  noted.  The  new  compound  con- 
sisted of  fine  irregular  bands  surrounding  some  of  the  orthosilicate 
grains  and  of  a  lower  index  and  double  refraction.  This  was 


76 


Original  Communications:  Eighth  International        [VOL. 


probably  the  compound  CaO.MgO.Si02  although  accurate  obser- 
vations on  the  bands  could  not  be  made  owing  to  their  minuteness. 
It  is  not  surprising  that  homogeneous  compounds  of  /3  orthosilicate 
containing  such  large  amounts  of  MgO  should  exist 
since  the  optical  properties  of  CaO.MgO.Si02  and  ft  2CaO.SiO2 
are  fairly  analogous  and  both  crystallize  in  the  orthorhombic 
system.  (See  Table  II- A). 

TABLE   II-A.     Orthosilicates  with  Molecular  Replacement 


Formula 

%MgO 

Temp. 

Time 

Characteristics 

2(.98  CaO,  .02  MgO).S:O2 

.93 

1500° 

12hrs. 

Dusting 

Homogeneous; 

elimin- 

consists of  B  or- 

ated 

thosilicate  with 

with 

mean  refractive 

reburn- 

index  lower  than 

ing 

1.725  that  of  the 

B  orthosilicate. 

2(.95  CaO,  .05  MgO).SiO2 

2.65 

1500° 

12  hrs. 

2(.934CaO,  .066MgO).  SiO2 

3.10 

1500° 

12  hrs. 

2(.91  CaO,  .09  MgO).SiO2 

4.82 

1500° 

12  hrs. 

The  minimum  re- 

fractive index 

was    approxi- 

mately 1.70. 

2(.894CaO,  .106  MgO).SiO2 

5.01 

1450° 

6  hrs. 

Non- 

Dust- 

ing. 

2(.882  CaO,  .118  MgO).SiO2 

5.59 

1450° 

6  hrs. 

2(.87  CaO,  .13  MgO).Si02 

6.18 

1450° 

6  hrs. 

Unhomogeneous 

consists  of  B  or- 

thosilicate and 

CaO.  MgO.  SiO2 

2(.86  CaO,  .14  MgO).SiO2 

6.66 

1450° 

5  hrs. 

2(.78  CaO,  .27  MgO).SiO2 

10.64 

1400° 

3  hrs. 

2(.50  CaO,  .50  MgO).SiO2 

25.57 

1400° 

2  hrs. 

The  tri-silicates  were  not  extensively  studied  since  in  these 
cements  under  examination  it  was  present  in  very  small  quanti- 
ties. However,  substitution  of  MgO  for  CaO  in  the  tri-silicate 
formula  gave  non-dusting  products.  The  clinkers  in  every  case 


Congress   of  Applied  Chemistry 


77 


were  soft  and  porous  and  lacked  the  hard  vitrification  of  the 
orthosilicate  containing  MgO.  Jesser1  also  states  that  MgO  re- 
places CaO  in  the  silicates  and  observed  the  formation  of  Monti- 
cellite.  (See  Table  II-B). 

TABLE  II-B.     Tricalcium  Silicates  with  Molecular  Replacement 


Formula 

%MgO 

Temp. 

Time 

Characteristics 

3(.962  CaO,  .038  MgO).SiO2 

2.01 

1500° 

5hrs. 

No 

Unhomogeneous  ; 

dust- 

consisted mainly 

ing. 

of    B    orthosili- 

3(.924 CaO,  .076  MgO).SiO2 

4.05 

1500° 

5hrs. 

Clinker 

cate  with     low- 

soft  and 

dere  index    and 

porous. 

considerable     a- 

3(.814  CaO,  .186  MgO).SiO2 

10.17 

1500° 

5hrs. 

mount  of  3  CaO. 

2  CaO.  MgO.  SiO2 

18.8 

1500° 

5  hrs. 

SiO2.    Free  CaO 

was  noted  in  all 

specimens     and 

free  MgO  in  only 

slight  amounts, 

except    in    the 

specimens  con- 

taining     10.17 

and  18.8%  MgO. 

In  those  mixes  in  which  percentage  replacement  was  practiced, 
dusting  was  reduced, vitrification  increased  considerable  ft  2CaO.- 
SiOa  and  a  little  3CaO.Si02  formed.  In  every  case  both  free  CaO 
and  free  MgO  were  present  in  the  dust.  (This  is  to  be  expected 
since  CaO  and  MgO  do  not  combine  with  equal  amounts  of  SiO2 
and  the  replacement  of  any  per  cent,  of  CaO  in  a  silicate  by  the 
same  per  cent.  MgO  would  give  an  excess  of  bases  over  acids.) 
Campbell  and  White3  state  that  the  more  reactive  CaO  enters 
into  combination  before  the  inert  MgO  leaving  to  the  latter  the 
task  of  displacing  CaO  till  equilibrium  is  reached.  Equilibrium 
is  not  reached  at  1500°  but  at  higher  temperatures  more  tri-sili- 


'Zent.  Hydraul.  Zement.  1,  41. 
2J.  Am.  Chem.  Soc.  28,  1273. 


78 


Original  Communications:  Eighth  International        [VOL. 


cate  would  be  formed  and  no  free  CaO  or  MgO  remain.  More- 
over, in  a  cement  raw  mix  formula  in  which  the  MgO  and  CaO 
are  calculated  together,  free  CaO  and  MgO  would  be  present  in 
the  clinkers  were  it  not  for  the  fact  that  additional  acids  in  the 
shape  of  A^Os  and  Fe20s  are  present  to  combine  with  them.  (See 
Table  H-C). 

TABLE  II-C.     Orthosilicates  with  Percentage  Replacement 


%MgO 

Temp. 

Time 

Characteristics 

2  CaO.  SiO2, 

1500° 

20  hrs. 

Dusting 

y  orthosilicate. 

persist- 

ed 

2(CaO  99%  MgO  1%)  SiO2 

1 

1500° 

8  hrs. 

Dust- 

Unhomogeneous; 

2(CaO  97%  MgO  3%)  SiO2 

3 

1500° 

8  hrs. 

ing  re- 

consisted of  B 

2(CaO  94%  MgO  6%)  Si02 

6 

1450° 

4  hrs. 

duced 

orthosilicate 

with 

with  lowered  in- 

reburn- 

dex   and   small 

ing. 

amount  of  3  CaO  . 

SiO2. 

2(CaO  90%  MgO  10%)  SiO2 

10 

1450° 

4  hrs. 

(Both   free  CaO 

and    MgO    in 

dust.) 

Continuing  with  the  aluminates,  mixes  were  made  corres- 
ponding to  3(mCaO.  nMgO.)  A12O3  in  which  m  and  n  were  varied 
to  give  MgO  in  %  varying  from  1-15.  None  of  the  5-3  alumi- 
nates were  made  since  this  compound  was  present  in  small  amounts 
in  the  cement,  and  its  formation  seems  to  depend  partly  on  the 
temperature  of  burning.  For  instance,  an  underburned  sample 
of  3-1  aluminate  would  contain  5-3  aluminate  and  free  CaO  due 
to  the  latter  not  entering  into  combination,  or  the  two  compounds 
might  be  present  in  a  high  burned  sample  due  to  the  dissociation 
of  the  3-1  aluminate,  it  being  unstable  at  its  melting  point. 
Shepherd  and  Rankin.1 

No  dusting  phenomena  were  noted,  simply  increased  vitrifi- 
cation and  lowering  of  the  fusing  point. 


.  Ind.  Eng.  Chem.  3,  212. 


v] 


Congress  of  Applied  Chemistry 


79 


The  microscopic  examination  revealed  homogeneity  up  to  10% 
MgO.  The  crystals  were  more  or  less  cubic  in  development, 
isotropic  and  the  index  of  refraction  varied  from  1.710  that  of 
C3aO.Al2O3  to  1.67,  that  of  the  specimen  containing  10%  MgO. 
Beyond  this  %  spinel,  MgO.Al2O3,  and  free  CaO  were  noted  to 
be  present.  Our  efforts  to  produce  homogeneous  products  of 
the  formula  2MgO.Al203or  3MgO.Al2O3  were  unsuccessful  which 
is  in  agreement  with  Shepherd  and  RankinV  statement  that 
only  one  compound  MgOAl.2O3  is  formed  in  the  binary  mixtures 
of  MgO  and  A12O3.  (See  Table  III).  No  ternary  systems  con- 
taining MgO  were  investigated  since  the  work  on  the  cements 
examined  seemed  sufficient  to  predict  its  actual  state  in  cements 
of  usual  MgO  content. 

TABLE  III.    Tricalcium  Aluminates  with  Molecular  Replacement 


%MgO 

Burn. 
Temp. 

Time 
Burn. 

3(.95  CaO,  .05  MgO).Al2O3 

2.24 

1420° 

2hrs. 

3(.91  CaO,  .09  MgO).Al2O3 

3.84 

1420° 

2hrs. 

3  (.89  CaO,  .11  MgO).Al2O3 

4.98 

1420° 

2hrs. 

3(.87  CaO,  .13  MgO).Al2O3 

5.91 

1420° 

2hrs. 

Homogeneous  crystals  of 

3(.845  CaO,  .155  MgO).Al2O3 

7.09 

1400° 

2hrs. 

cubical  development  with 

3(.82CaO,  .18MgO).Al2O3 

8.26 

1400° 

2hrs. 

refractive  index  <O  -7  10, 

3(.8CaO,  .2MgO).Al2O3 

9.2 

1400° 

2  hrs. 

that  of  3  CaO.  A12O3. 

3(.79  CaO,  .21  MgO).Al2O3 

9.69 

1350° 

3  hrs. 

3(.78  CaO,  .22  MgO).Al2O3 

10.1 

1350° 

3  hrs. 

Traces    of    inhomogene- 

ity;  tricalcium  alumin- 

ate  has  refractive  index 

of  1.67.    MgO.Al2O3and 

CaO  present. 

3(.76  CaO,  .24  MgO).Al2O3 

11.1 

1350° 

3  hrs. 

Unhomogeneous;    trical- 

3(.74 CaO,  .26  MgO).Al2O3 

12.1 

1350° 

3  hrs. 

cium  aluminate  with  in- 

3(.6S CaO,  .32  MgO).Al2O3 

15.7 

1350° 

3  hrs. 

dex  of  1.67.    MgO.Al2O8 

and  CaO  present. 

Considering  the  compounds  and  cements  examined,  it  has  been 
shown  that  MgO  up  to  6%  in  the  orthosilicate  and  10%  in  the 
tri-aluminate  forms  homogeneous  compounds  with  CaO,  and  in 


1Am.  J.  Sc.  28,  314. 


80  Original  Communications:  Eighth  International        [VOL. 

Portland  cement  up  to  7.5%  may  exist  without  being  present  as 
MgO  or  MgO.Al203,  without  considering  any  possible  action  of 
Fe20s,  which  Jesser1  states  increases  the  limit  for  homogeneity. 
Therefore,  the  chances  of  MgO  remaining  free  in  any  cement  are 
exceedingly  remote  since  ordinarily  cements  do  not  contain  in 
excess  of  4%.  If  then  due  to  composition,  temperature  and  time 
of  burning,  the  ft  orthosilicate  and  tri-aluminate  are  formed  the 
MgO  will  form  homogeneous  compounds  with  the  CaO  until 
the  limit  of  homogeneity  has  been  reached.  Beyond  this  we 
may  have  formed  CaO.MgO.SiO2  and  MgO.Al2O3.  We  may 
further  state  that  in  the  Portland  cements  examined  in  this  labor- 
atory the  ft  orthosilicate  has  been  the  most  important  constituent 
and  the  tri-aluminate  with  very  few  exceptions  has  also  been  an 
important  compound  present.  The  limit  of  homogeneity  will 
vary  according  to  the  relative  amounts  of  these  two  compounds 
present,  and  may  be  still  further  increased  by  the  presence  of 
3CaO.SiO2  which  we  have  reason  to  believe  may  contain  some 
MgO. 

From  the  facts  stated  it  would  seem  impossible  that  any  dis- 
integration or  falling  off  in  strength  of  MgO  cements  should  be 
ascribed  to  the  presence  of  free  MgO  in  the  clinkers. 

In  considering  high  MgO  cements  the  objection  to  them  seems 
to  be  that  they  are  liable  to  swell  and  fall  off  in  strength  with 
time  intervals  of  a  year  or  more.  The  literature  on  the  subject 
of  MgO  cements  as  regards  their  physical  behavior  is  voluminous 
and  contradictory  and  will  not  be  considered  here. 

It  is  generally  considered  that  the  MgO  compounds  have  no 
hydraulic  properties  and  do  not  hydrate,  or  in  any  case  hydrate 
very  slowly.  The  entrance  of  MgO  on  the  CaO  compounds  cer- 
tainly affect  their  hydration  and  other  physical  properties  in  a 
manner  which  cannot  be  predicted  in  advance  since  the  proper- 
ties of  such  compounds  so  often  differ  from  those  of  the  separate 
constituents.  For  this  reason  the  physical  properties  of  the 
Ca  silicates  and  aluminates  are  being  investigated,  and  from  these 
results  it  is  hoped  that  a  satisfactory  explanation  as  to  the  be- 
havior of  MgO  in  cements  may  be  found. 


.  Hydraul.  Zement.  1,  42. 


v]  Congress  of  Applied  Chemistry  81 

SUMMARY 

1 .  The  examination  of  a  number  of  Portland  cements  showed 
that  7.5%  MgO  may  be  present  without  being  in  the  form  of 
MgO  or  MgO.Al203. 

2.  MgO  can  form  homogeneous  compounds  with  CaO  in  the 
/?2CaO2Si02  up  to  6%;  beyond  this  a  mixture  of  /?  orthosilicate 
and  CaO.MgO.SiO2  is  formed. 

3.  MgO  can  form  homogeneous  compounds  with  CaO  in  the 
3-1  aluminate  up  to  10%;  beyond  this  a  mixture  of  3-1  aluminate, 
MgO.Al2O3,  and  free  CaO  is  present. 

4.  MgO  acting  as  a  flux  assists  in  the  formation  of  /32CaO.- 
SiO2  and  3CaO.Si02. 


THE  USE  OF  THE  HIGHER  PHENOLS  IN  TESTING 
FOR  FREE  LIME  IN  PORTLAND  CEMENT 

BY  DAVID  C.  MCFARLAND  AND  HARRY  F.  HADLEY 

University  of  Illinois,    Urbana,  Illinois. 

A  great  deal  of  effort  has  been  spent  in  the  attempt  to  find  an 
adequate  method  for  the  determination  of  free  lime  in  Portland 
Cement.  The  literature  of  the  subject  is  extensive,  and  numerous 
tests  involving  extraction  with  water  and  with  aqueous  or  non- 
aqueous  solvents  have  been  proposed.  The  majority  of  these 
have  proven  unsatisfactory  and  have  been  shown  to  give  either 
too  high  results  owing  to  decomposition  of  the  calcium  compounds 
in  the  cement  or  too  low  results  on  account  of  incomplete  reaction 
of  the  free  lime  present. 

Probably  the  best  test  yet  proposed  is  that  of  Alfred  H.  White1 
which  depends  upon  the  fact  that  free  calcium  oxide  and  calcium 
hydroxide  have  been  found  to  give  crystals  of  calcium  phenolate 
when  a  solution  of  phenol  in  some  immiscible  and  rather  non- 
volatile solvent,  such  as  nitro-benzene,  along  with  a  trace  of 
water  is  added  to  cement  containing  free  lime.  The  crystals  are 
easily  detected  by  the  aid  of  a  polarizing  microscope  and  an  ap- 
proximate idea  of  the  amount  of  free  lime  may  be  formed  by  the 
relative  number  of  crystals  and  their  rapidity  of  formation. 

A.  G.  Smith2  has  used  this  test  in  routine  mill  work  and  has 
found  that  it  checks  very  well  with  the  boiling  test  for  soundness. 

Reibling  and  Reyes3  have  studied  the  test  in  detail  and  its 
applicability  to  the  testing  of  commercial  cements.  They  con- 
clude that4  " White's  test  offers  a  positive  means  for  the  identi- 
fication of  sintered,  non-sintered  and  hydrated  free  lime  in  such 
materials  as  Portland  Cement;  however,  only  an  experienced 


Journal  Industrial  &  Engineering  Chemistry,  1  5-11  January  1909. 
2 Journal  Industrial  &  Engineering  Chemistry  1,  668-670. 
3Philippine  Journal  Science  V  (A)  367-415,  Dec.  1910. 
4Loc.  cit.  page  379. 

83 


84  Original  Communications:  Eighth  International        [VOL. 

operator  who  thoroughly  understands  the  conditions  of  the  reac- 
tion in  which  three  different  characteristic  habits  of  the  same 
crystal  can  be  produced  under  given  circumstances  can  do  this 
successfully. " 

The  chief  drawback  to  the  White  test  is  the  fact  that  it  is  not 
quantitative  or  at  the  best  is  only  relatively  so,  and  it  was  with 
the  hope  of  finding  a  quantitative  method  that  this  investigation 
was  taken  up.  In  this  work  we  have  investigated  the  formation 
of  compounds  by  reaction  of  the  higher  homologues  of  phenol 
with  lime  and  their  solubility  in  various  solvents  with  the  hope 
that  one  might  be  found  which  would  be  easily  formed,  and  hav- 
ing a  uniform  composition  and  a  solubility  which  would  enable 
it  to  be  quantitatively  extracted  by  means  of  a  suitable  solvent. 

The  calcium  compound  formed  with  phenol  and  described  by 
White  and  by  Reibling  and  Reyes  was  first  prepared  as  follows: 
One  half  gram  of  calcium  oxide  made  from  Kaulbaum's  C.  P. 
Calcium  Carbonate  by  heating  it  in  a  porcelain  crucible  over  a 
blast-lamp,  was  placed  in  a  tube  containing  30  c.c.  of  ether.  To 
this  were  added  25  moles  of  phenol  and  one  cubic  centimeter  of 
water.  The  reaction  required  some  time  for  its  completion  and 
the  mixture  was  shaken  mechanically  for  twenty-four  hours  to 
make  it  complete. 

At  the  end  of  this  time  the  salt  was  filtered  off,  washed  care- 
fully with  ether  and  dried  for  a  short  time  in  the  air,  giving  a 
perfectly  white  powder. 

The  analysis  was  carried  out  by  igniting  a  weighed  portion  of 
the  salt  in  a  weighed  platinum  dish  and  finding  the  weight  of  the 
residual  calcium  oxide.  The  result  was  as  follows: 

.2786  gram  of  the  salt  gave  .1159  gram  CaO 
Calculated  for  C6H5OCaOH  CaO  =  37.31% 

Found  CaO  =  41.60% 

This  indicates  that  a  considerable  amount  of  unchanged  lime 
remained  enclosed  in  the  calcium  salt.  On  account  of  the  ex- 
treme ease  with  which  the  salt  undergoes  hydrolysis  when  dis- 
solved in  water  it  was  impracticable  to  free  it  from  the  excess  lime 
by  recrystallization  from  water.  The  same  difficulty  was  found 
with  the  other  salts  of  this  series  prepared  later. 


v]  Congress  of  Applied  Chemistry  85 

The  phenol  salt  is  moderately  soluble  in  water  and  difficultly 
so  in  ethyl  alcohol,  methyl  alcohol,  chloroform,  ether,  benzene, 
toluene,  ligroin,  turpentine  and  pyridine.  No  solvent  was  found 
with  which  it  would  be  practical  to  extract  the  salt  from  cement. 

Similar  experiments  were  carried  out  with  A  Naphthol,  B 
Naphthol,  ortho  ethyl  phenol  carvacrol,  thymol,  1,  3,  4,  xylenol, 
ortho  cresol,  para  cresol  and  para  nitro  cresol.  Each  of  these 
substances  reacted  with  lime  to  some  extent  as  was  shown  in  the 
cases  of  B  Naphthol,  ortho  ethyl  phenol,  1,  3,  4,  xylenol  and  para 
cresol,  by  the  formation  of  colored  compounds  and  in  all  cases 
by  the  results  of  the  analysis  of  the  product.  However,  only 
B  Naphthol  and  para  cresol  were  comparable  with  phenol  in  the 
extent  of  their  reaction.  Both  of  these  reacted  more  easily  than 
phenol. 

B  Naphthol  united  readily  with  pure  lime  forming  a  slightly 
dark  colored  compound.  An  analysis  of  the  material  after  wash- 
ing with  ether  and  drying  gave  the  following  result: 

.2177  gram  of  the  salt  gave  .0577  gram  CaO 
Calculated  for  Ci0H7OCaOH  CaO  =  28.00% 

Calculated  for  Ci0H7OCaOH,  H2O  CaO  =  25.70% 
Found  CaO  =  26.50% 

This  salt  decomposed  when  left  standing  in  the  air.  It  is  not 
soluble  to  any  great  extent  in  water  and  is  practically  insoluble 
in  methyl  and  ethyl  alcohol  and  in  ligroin. 

Para-cresol  reacted  immediately  with  pure  lime  producing  a 
deep  red  colored  salt.  The  reaction  took  place  much  more 
rapidly  than  that  with  either  phenol  or  B  Naphthol. 

.2247  gram  of  salt  gave  .0759  gram  CaO 
Calculated  for  C6H4  CH3OCaOH  CaO  =  33.53 
Found  CaO  =  33.77 

This  salt  dissolved  slightly  in  water  producing  a  red  solution. 
Hydrolysis  took  place  in  this  solution  almost  immediately.  The 
salt  is  slightly  soluble  in  dilute  alcohol  but  is  hydrolyzed  in  this 
solvent  also.  It  is  difficultly  soluble  in  absolute  ethyl  and  methyl 
alcohol,  ether,  carbon  disulphide  acetone,  benzene  and  ligroin. 
The  salt  was  most  soluble  in  a  mixture  of  water,  alcohol,  and 


86 


Original  Communications:  Eighth  International        [VOL. 


para  cresol  and  it  seemed  possible  that  this  mixture  could  be  used 
as  a  means  of  extracting  the  salt  from  cement  after  it  had  been 
formed  by  the  action  of  para  cresol  on  the  free  lime.  Experi- 
ments of  the  following  nature  were  carried  out  to  test  this  possi- 
bility. A  weighed  amount  of  cement  or  a  mixture  of  cement 
with  pure  lime  was  treated  with  alcohol  which  contained  a  trace 
of  water.  Then  para  cresol  was  added  and  the  mixture  mechan- 
ically shaken  for  an  hour  or  for  such  a  length  of  time  as  seemed 
necessary  to  allow  the  reaction  of  the  calcium  oxide  or  hydroxide 
present  with  the  added  cresol.  The  liquid  was  then  filtered  from 
the  cement,  the  residue  washed  with  water  until  the  washings 
were  no  longer  colored,  the  filtrate  evaporated  to  dryness  in  a 
porcelain  dish  and  the  residue  ignited  and  weighed  as  calcium 
oxide.  A  large  number  of  experiments  were  carried  out  along  this 
general  line,  the  conditions  being  varied  extensively  in  order  to 
determine  those  which  would  give  the  best  extraction.  The  fol- 
lowing table  shows  the  results  of  a  portion  of  these  experiments 
together  with  the  conditions  of  each. 


g 

ll 

3 

1 

li 

*1 

, 

i 

o 

CJ-0 

H 
"8 

1 

Ig 

•3* 

OJ  ^ 

!| 

*! 

2o| 

1 

c> 

o 

*o  a 

°.  li 

a  -^ 

"1 

*o  £ 

o  •§ 

o.— 

I  "M 

1 

!? 

51 

o 

o 

8l 

8 

£    § 

Q 

o 

28 

Cement  A 

3 

.00 

1 

21 

.00 

.1 

30 

.0436 

29 

3 

.00 

1 

21 

.00 

.5 

10 

.0397 

30 

3 

.00 

1 

21 

.00 

.1 

30 

.0419 

31 

3 

.06 

1 

21 

.00 

.5 

30 

.1186 

32 

3 

.09 

1 

21 

.00 

.5 

30 

.1448 

33 

3 

.15 

1 

21 

.00 

.5 

30 

.1909 

34 

3 

.00 

1 

21 

.00 

.5 

30 

.0796 

* 

35 

Cement  B 

3 

.00 

1 

21 

.00 

.5 

30 

.0332 

36 

3 

.03 

1 

21 

.00 

.5 

30 

.0558 

37 

3 

.06 

1 

21 

.00 

.5 

30 

.0797 

38 

3 

.15 

1 

21 

.00 

.5 

30 

.1272 

*The  cement  and  lime  were  finely  ground  together  before  being  used  in 
the  experiment. 


v] 


Congress  of  Applied  Chemistry 


87 


w 
e 

i 

Gr.  of  cement 
and  lime  used 

a 

o  -j 

0 

d 
11 

CC.  of  absolute 
alcohol 

fi 
sj 

g" 

F 

Grams  of  CaO 
extracted 

-2 
2 

1 

39 

Cement  B 

3 

.15 

1 

21 

.00 

.1 

30 

.1110 

40 

Cement  C 

3 

.00 

1 

21 

.00 

.5 

30 

.1055 

41 

3 

.03 

1 

21 

.00 

.5 

30 

.1318 

42 

3 

.06 

1 

21 

.00 

.5 

30 

.1390 

43 

3 

.09 

1 

21 

.00 

.5 

30 

.1767 

44 

3 

.15 

1 

21 

.00 

.5 

30 

.1880 

45 

3 

.00 

1 

21 

.00 

.5 

30 

.1070 

* 

46 

Cement  D 

3 

.00 

1 

21 

.00 

.5 

30 

.0893 

47 

3 

.03 

1 

21 

.00 

.5 

30 

.1173 

48 

3 

.06 

1 

21 

.00 

.5 

30 

.1089 

49 

3 

.09 

1 

21 

.00 

.5 

30 

.1631 

50 

3 

.15 

1 

21 

.00 

.5 

30 

.1586 

51 

3 

.00 

1 

21 

.00 

.5 

30 

.0789 

* 

57 

3 

.03 

6 

21 

.00 

.5 

30 

.1106 

58 

3 

.06 

6 

21 

.00 

.5 

30 

.1292 

59 

3 

.09 

6 

21 

.00 

.5 

30 

.1632 

60 

3 

.15 

6 

21 

.00 

.5 

30 

.1663 

61 

3 

.15 

1 

21 

.00 

.5 

60 

.1850 

64 

3 

.15 

1 

21 

.00 

.5 

30 

.1500 

* 

65 

3 

.15 

1 

21 

.00 

.5 

60 

.1336 

* 

66 

3 

.15 

1 

21 

.00 

.5 

60 

.2025 

1* 

67 

3 

.15 

1 

42 

.00 

.1 

60 

.2078 

1* 

70 

3 

.15 

1 

00 

.21 

30 

.1941 

1* 

71 

3 

.15 

1 

00 

.21 

60 

.2049 

1* 

72 

3 

.15 

1 

00 

.50 

60 

.2132 

1* 

73 

Cement  B 

3 

.00 

1 

00 

.21 

60 

.0557 

1** 

74 

3 

.15 

1 

00 

.21 

60 

.1722 

1** 

irThe  residue  on  the  filter  was  washed  with  75  cc.  of  water. 

*The  cement  and  lime  were  finely  ground  together  before  being  used  in  the 
experiment. 

**The  cement  and  lime  were  ground  together  only  enough  to  break  up  the 
small  lumps  of  lime. 


88  Original  Communications:  Eighth  International       [VOL. 

The  best  extractions  were  obtained  by  adding  21  c.c.  of  ab- 
solute alcohol,  30  drops  of  para  cresol  and  0.5  c.c.  of  water  to  3 
grams  of  cement  to  be  tested  and  proceeding  as  above  outlined. 

As  may  be  seen  from  the  table  the  results  were  hardly  satisfac- 
tory from  a  quantitative  standpoint.  Where  only  small  addi- 
tions of  lime  had  been  made,  the  increased  amount  of  lime  ex- 
tracted .  corresponded  fairly  well  with  the  amount  of  lime  added. 
But  with  increasing  additions  of  lime  the  percentage  of  extrac- 
tion fell  off  so  that  it  did  not  give  the  total  amount  present. 
It  was  also  found  difficult  to  get  duplicate  determinations  to  check 
very  closely. 

The  best  that  can  be  said  for  the  method  as  used  is  that  under 
uniform  conditions  the  extraction  will  be  approximately  quanti- 
tative when  small  amounts  of  lime  are  involved. 

MODIFICATION  OF  WHITE'S  PHENOL  TEST  FOR  FREE  LIME 

Because  of  the  rapidity  with  which  B-naphthol  and  p-cresol 
reacted  with  free  lime,  it  was  decided  to  try  a  modification  of 
White's  test  using  these  substances  instead  of  phenol.  Equal 
weights  of  b-naphthol  were  added  to  nitro  benzene,  xylene,  a- 
bromnaphthalene  and  machine  oil.  A  drop  of  water  was  added 
to  each  of  these  mixtures.  The  mixtures  were  then  tried  upon 
both  pure  calcium  oxide  and  a  cement  to  which  5%  calcium  oxide 
had  been  added.  In  no  case  did  crystals  form,  which  resembled 
calcium  phenolate  crystals;  however,  when  the  solvent  evapo- 
rated crystals  of  b-naphthol  were  formed. 

The  test  was  next  tried  with  p-cresol.  It  is  to  be  understood 
that  any  of  the  following  reagents,  which  are  named,  contain 
equal  parts  of  p-cresol  and  the  solvent  together  with  a  trace  of 
water,  p-cresol  with  nitrobenzene  did  not  give  crystals.  With 
xylene,  crystals  resembling  those  of  calcium  phenolate  were 
formed  when  the  reagent  was  added  to  a  cement,  which  contained 
5%  free  lime.  These  crystals  resembled  the  crystals  of  calcium 
phenolate  excepting  that  they  were  a  pale  red  color.  On  account 
of  this  latter  characteristic  they  could  be  distinguished  very 
easily  with  the  ordinary  microscope,  thus  making  their  identifi- 
cation possible  without  the  use  of  the  polarizing  microscope.  A 


v]  Congress   of  Applied  Chemistry  89 

reaction  with  pure  calcium  oxide  took  place  immediately  as  was 
shown  by  the  formation  of  the  red  salt,  but  no  crystals  were 
formed.  When  kerosene  was  used  as  a  solvent,  crystals  were 
produced  both  in  pure  lime  and  in  the  cement,  which  contained 
5%  lime;  crystals  were  also  formed  when  machine  oil  was 
used. 

By  far  the  best  solvent  used  was  found  to  be  absolute  alcohol. 
One  c.c.  of  p-cresol,  3  cc.  of  absolute  alcohol  and  4  drops  of  water 
were  used  to  make  this  reagent.  The  following  tests  were  made : 
The  cement  containing  5%  lime  gave  crystals  within  2  minutes. 
Cements  B,  D,  and  C,  and  cement  E;  samples  No.  1,  3,  4,  all 
gave  crystals  within  2-3  minutes.  A  sample  of  cement  A,  which 
had  been  exposed  to  the  air  for  about  three  months  was  tested. 
This  gave  a  few  crystals  at  the  end  of  15  minutes,  showing  that 
free  lime  was  very  scarce.  Cement  E,  sample  No.  6,  gave  a  very 
few  crystals  within  10  minutes,  while  sample  No.  5  gave  no  crys- 
tals within  20  minutes.  A  cement,  which  had  once  contained 
free  lime,  but  which  had  been  exposed  to  carbon  dixoide  for  two 
months  was  tested.  It  gave  a  very  few  crystals  within  15 
minutes. 

As  stated  above,  cement  E,  sample  No.  5,  and  the  exposed 
cement  A  did  not  give  crystals  for  a  long  time.  These  two 
cements  were  ground  in  a  mortar  and  again  tested  for  free  lime. 
Cement  A  gave  crystals  within  1.6  minutes  and  cement  E,  No.  5, 
gave  an  abundance  of  crystals  within  4  minutes.  Free  lime  must 
have  been  liberated  by  the  grinding,  otherwise  the  time  it  took 
the  crystals  to  form  would  have  been  the  same  in  both  cases. 
The  experiment  therefore  shows  the  effect  of  aging  on  free  lime, 
i.  e.,  free  lime  on  the  outside  of  the  particles  of  cement  being 
attacked,  while  the  free  lime  on  the  inside  was  not  affected. 
Aging  of  cement  does  not  necessarily  do  away  with  free  lime. 
Obviously  a  coating  was  formed  on  the  outside  of  the  particle, 
which  was  not  penetrated  by  carbon  dioxide  and  moisture.  This 
accords  with  the  results  obtained  by  Reibling  and  Reyes.1 


ibling  and  Reyes,  Loc.  cit  page  398. 


90  Original  Communications:  Eighth  International       [VOL. 

CONCLUSIONS 

From  the  above  experimental  facts  the  following  conclusions 
may  be  drawn: 

First.  That  calcium  phenolate  and  the  calcium  salts  of  homo- 
logues  of  phenol  are  very  difficultly  soluble  in  any  of  the  common 
solvents. 

Second.  That  phenol  and  its  homologues  do  not  at  all  act 
with  the  same  rapidity,  or  to  the  same  degree  of  completeness  with 
free  lime.  P-cresol  apparently  reacts  immediately;  b-naphthol 
arid  phenol  do  not  react  so  rapidly  and  the  remaining  homo- 
logues, which  were  tried,  react  only  slightly. 

Third.  That  a  roughly  quantitative  extraction  of  free  lime  is 
possible  by  means  of  a  properly  proportioned  mixture  of  para 
cresol,  with  absolute  alcohol,  and  a  trace  of  water,  when  the  total 
quantity  of  lime  is  small.  The  method  does  not  give  good  results 
with  large  quantities  of  free  lime. 

Fourth.  That  p-cresol  with  alcohol  and  a  trace  of  water  gives 
a  more  rapid  test  for  free  lime  than  White's  test.  Also  the  test 
is  more  delicate  for  it  will  give  an  abundance  of  crystals  where 
White's  test  gave  only  a  few.  Apparently  the  test  is  too  delicate 
for  practical  use. 

Fifth.  That  the  aging  of  cement  for  a  period  of  time  does  not 
necessarily  destroy  all  the  free  lime,  which  it  contains. 


THE  PHYSICAL  AND  CHEMICAL  PROPERTIES  OF 
PORTLAND  CEMENT 

BY  W.  C.  REIBLING  AND  F.  D.  REYES 
Bureau  of  Science,  Manila,  P.  I.     ' 

INTRODUCTION 

The  main  effort  in  this  work  was  directed  toward  a  study  of 
those  characteristics  of  Portland  cement  regarding  which  there 
exists  the  greatest  amount  of  misconception  and  diversity  of 
opinion,  our  object  being  to  assist  in  the  universal  effort  to  formu- 
late cement  specifications  so  drawn  as  to  guarantee  the  manufac- 
ture and  use  of  Portland  cement  of  the  quality  sought  for. 

Our  investigations  were  conducted  on  many  grades  and  brands 
of  material,  careful  consideration  being  given  to  the  conditions 
of  burning,  grinding  and  seasoning  to  which  the  various  products 
had  been  subjected.  After  working  on  commercial  products, 
the  investigations  were  continued  on  non-aerated  clinker  received 
from  manufacturers  in  Europe  and  China.  Finally,  one  of  the 
authors  visited  a  few  large  cement  factories  where  every  courtesy 
was  shown  him  and  where  he  was  enabled  to  secure  valuable 
information  and  to  collect  special  material  for  this  work. 

The  endeavor  at  first  was  to  ascertain  the  significance  of  the 
ultimate  chemical  composition.  Within  wide  limits  no  apparent 
relationship  between  the  ultimate  chemical  composition  and  the 
physical  properties  of  the  various  cements  could  be  discovered. 
This  made  necessary  a  more  comprehensive  investigation  which 
for  the  sake  of  brevity  and  clearness  was  presented,  as  far  as 
possible,  as  an  abstract  of  the  results,  a  general  summary  of  which 
follows. 

PART  I 

Free  Lime  in  Portland  Cement 

(1)  As  our  investigations  progressed  it  soon  became  evident 
that  the  Portland  cements  examined  all  contained  free  lime  and 

91 


92  Original  Communications:  Eighth  International       [VOL. 

that  their  physical  properties  were  influenced  to  a  marked  degree 
not  only  by  the  amount  of  free  lime,  but  also  by  its  condition; 
that  is,  whether  this  calcium  was  present  as  the  hydroxide,  oxide, 
or  as  the  latter  heated  to  a  degree  of  incipient  fusion. 

(2)  In  order  to  obtain  reliable  information  about  free  lime 
the  method  for  its  detection  first  discovered  by  A.  H.  White1  was 
employed.     However,  in  order  to  make  this  test  efficient  and 
accurate,  a  chemical  and  microscopic  investigation  of  the  forma- 
tion of  calcium  hydroxide-phenol  crystals  was  necessary.     The 
result  of  this  investigation  and  the  manner  in  which  it  is  possible 
to  determine  relative  amounts  of  free  lime  and  to   distinguish 
between  that  which  is  sintered,  non-sintered,  or  slaked,  are  fully 
described. 

(3)  The  application  of  this  test  gave  conclusive  proofs  of  the 
presence  and  the  effects  of  free  lime  in  commercial  Portland 
cements,  and  a  study  of  this  free  lime  under  different  condi- 
tions of  burning,  grinding  and  seasoning  showed  the  following 
results. 

A.     Concerning  the  degree  of  burning: 

(a)  That  as  the  kiln  temperature  increased,  non-sin- 

tered calcium  oxide  gradually  became  converted 
into  a  sintered  state  having  different  physical 
properties. 

(b)  That  this  conversion  may  occur  at  temperatures  far 

below  those  necessary  for  the  proper  burning 
of  the  cement. 

(c)  That  underburned  cement  may  contain  both  sin- 

tered   and    non-sintered    lime. 

(d)  That  all  of  the  free  lime  in  hard-burned  cement 

is  sintered. 

(e)  That  Portland  cement  clinker  can  be  burned  per- 

fectly so  as  neither  to  contain  free  lime  nor  have 
lime  liberated  in  the  ordinary  process  of  cooling 
and  grinding. 


'Journ.  Ind.  &  Eng.  Chem.  (1909),  1,  5. 


v]  Congress  of  Applied  Chemistry  93 

B.  Concerning  the  effects  of  seasoning: 

(a)  That  non-sintered  lime  hydrates  more  readily  and 

quickly  than  sintered  lime. 

(b)  That  sintered  lime  may  hydrate  so  slowly  by  mere 

exposure  to  the  atmosphere  that  the  action  takes 
place  essentially  on  the  outer  exposed  parts  of  the 
particles  and  only  gradually  penetrates  to  the 
interior. 

(c)  That  aeration  tends  completely  to  convert  at  least 

the  surfaces  of  the  hydrated  lime  into  carbonate. 

(d)  That  the  penetration  of  air  into  a  mass  of  ground 

cement  is  limited  approximately  to  a  thin  outer 
layer. 

(e)  That  when  cement  is  aerated  in  thin  layers  the 

conversion  into  carbonate  goes  on  practically  as 
fast  as  hydration. 

(f )  That  aeration  tends  to  coat  the  particles  of  sintered 

lime  with  an  impermeable  film  of  calcium  car- 
bonate so  that  even  thoroughly  aerated,  finely 
ground  cement  may  contain  unslaked  free  lime. 

C.  Concerning  the  effect  of  free  lime  upon  the  soundness: 

(a)  That  the  usual  cause  of  unsoundness  is  unslaked 

free  lime. 

(b)  That  the  effect  of  free  lime  upon  the  soundness  is 

influenced  by  the  cohesive  properties  of  the  ce- 
ment, the  "speed  of  slaking,"  fineness,  the  tem- 
perature and  amount  of  water  used  in  gauging, 
and  the  effect  of  impurities  and  retarders. 

(c)  That  the  test  for  soundness  as  indicating  the  pres- 

ence of  free  lime  are  relatively  crude  as  compared 
with  the  microscopic  study  of  calcium  hydrox- 
ide-phenol crystals. 

(d)  That  slaked  lime  does  not  cause  failure  in  sound- 

ness tests. 

(e)  That  non-sintered  lime  must  be  present  in  quan- 

tity to  cause  unsoundness,  and  if  it  is  so  present, 
the  disruption  is  likely  to  occur  in  water  and  air, 
as  well  as  in  steamed  pats. 


94  Original  Communications:  Eighth  International       [VOL. 

(f)  That  a  fair  amount  of  fused  sintered  lime  is  liable 

to  cause  unsoundness  in  the  accelerated  tests. 

(g)  That  fineness  assists  soundness. 

(h)  That  the  agreement  between  the  microscopic  evi- 
dence and  the  result  of  tests  for  soundness  was 
very  close. 

PART  II 

The  Seasoning  of  Portland  Cement 

(4)  The  preliminary  work  had  shown  that  although  seasoning 
improves  the  soundness  of  unsound  cements,  it  often  works  seri- 
ous injury  to  the  strength  and  setting  properties  of  sound  prod- 
ucts.     Also,  that  different  methods  of  seasoning  and    storing 
the  same  material  usually  produced  different  effects  upon  the 
physical  and  chemical  properties,  and  that  the  different  cements 
were  influenced  in  unlike  manner  by  the  same  conditions  of  sea- 
soning.    Cements  stored  in  air-tight  receptacles  underwent  little 
or  no  change.     Therefore,  a  thorough  study  was  made  of  the 
absorption  of  volatile  constituents  by  both  clinkers  and  pulver- 
ized cement. 

(5)  Working  with  the  finished  product  the  following  became 
evident : 

(a)  That  air  penetrates  very  little  (less  than  13  millimeters) 

into  a  mass  of  undisturbed  cement;  however,  water 
absorbed  from  the  atmosphere  may  slowly  penetrate 
farther. 

(b)  That  cements  exposed  to  the  air  in  small,  repeatedly  re- 

mixed quantities  show  the  greatest  increase  in  the  per- 
centage of  carbon  dioxide.  This  confirmed  the  micro- 
scopic evidence  that  the  free  lime  in  Portland  cement 
exposed  to  the  atmosphere  changes  to  carbonate  soon 
after  hydrating,  the  tendency  being  to  coat  the  individ- 
ual particles  with  calcium  carbonate. 

(c)  That  cements  stored  in  air-tight  receptacles  show  a  slow 

decrease  in  the  percentage  of  moisture,  due  as  evinced 
by  the  microscopic  evidence,  to  the  slaking  of  free  lime. 


v]  Congress  of  Applied  Chemistry  95 

(d)  That  the  rate  of  absorption  decreases  very  rapidly  as  the 

reaction  proceeds,  fine  particles  absorbing  proportion- 
ally more  than  coarser  ones. 

(e)  That,  atmospheric  conditions  being  the  same,  the  quan- 

tity and  rapidity  of  absorption  depends  largely  upon 
the  quality  and  quantity  of  free  lime. 

(6)  Contrary  to  the  results  obtained  with  ground  material, 
it  often  proves  more  difficult  to  remove  the  cause  of  unsoundness 
from  hard-burned  than  from  underburned  clinkers.     The  reason 
for  this  is  that  perfectly  sintered  clinker  is  practically  inert  to 
water  and  atmospheric  influence  and  consequently  the  free  lime 
imbedded  in  this  hard,  dense,  inert  magma  is  more  thoroughly 
protected  than  the  free  lime  in  underburned  clinker. 

(7)  This  work  together  with  a  study  of  manufacturing  prac- 
tices and  the  strength  developed  by  hard-burned  and  underburned 
cements  lead  to  the  following  conclusions: 

(a)  That  aeration  is  the  least  efficient  practical  method  of 

seasoning  Portland  cement. 

(b)  That  a  high  loss  by  ignition  and  a  corresponding  low  spe- 

cific gravity  are  not  characteristic  of  commercial  cements 
made  from  well-burned  clinker. 

(c)  Cement  made  entirely  from  underburned  clinker  seldom 

appears  on  the  market  except  as  hydraulic  limes.  It 
would  fail  to  pass  the  test  of  strength.  Underburned 
cement  usually  comes  to  the  consumer  mixed  with  the 
harder  burned  material  from  the  same  mill  and  our 
present  specifications  are  such  that  a  mixture  of  45  per 
cent,  of  disintegrated  clinker  and  55  per  cent,  of  sound 
clinker  passed  all  requirements  except  the  percentage 
loss  by  ignition.  This  emphasizes  the  real  importance 
and  great  value  of  the  test  for  volatile  constituents. 

(d)  The  best  set  kiln  process  yields  a  considerable  amount  of 

underburned  clinker.  Some  manufacturers  sort  this 
out  very  carefully.  Others  do  very  little  or  no  sorting 
and  their  finished  product  is  not  true  Portland  cement 
but  a  mixture  of  seasoned  underburned  and  well-burned 
cement  containing  sintered,  nonsintered  and  hydrated 


96  Original  Communications:  Eighth  International       [VOL. 

free  lime,  calcium  carbonate,  and  fused  and  sintered 
compounds  of  many  kinds. 

(e)  The  rotary  kiln  is  capable  of  producing  a  more  uniformly 
burned  clinker  than  the  set  kiln.  Extreme  fineness  in 
the  grinding  of  the  raw  material  is  necessary  to  produce 
a  perfectly  sintered  product.  Few  manufacturers 
grind  fine  enough,  the  majority  producing  a  hardburned 
clinker  but  one  which  still  contains  a  considerable  per- 
centage of  free  lime  some  of  which  fails  to  slake  before 
induration  and  causes  the  much-discussed  character- 
istic drop  in  the  strength  of  rotary  cements. 

PART  III 
The  Setting  Properties  of  Portland  Cement 

(8)  For  determining  the  time  of  initial  and  final  set  the 
method  employing  the  Vicat  needle  was  found  to  be  reliable, 
impartial  and  accurate,  abnormal  results  being  obtained  only 
with  cements  of  very  poor  quality. 

(9)  Preliminary   experiments   on   the   setting   properties   of 
commercial  products  demonstrated: 

(a)  That  although  cements  of  different  chemical  composition 

have  different  natural  setting  tendencies,  changes  in 
the  setting  properties  were  due  primarily  to  the  absorp- 
tion of  water  or  water  and  carbon  dioxide. 

(b)  That  changes  in  the  setting  properties  were  independent 

of  the  ultimate  chemical  composition,  the  fineness,  the 
amount  of  retarder,  or  the  quantity  of  water  and  carbon 
dioxide  absorbed. 

(c)  That  further  consideration  of  the  nature  of  the  raw  ma- 

terials used  or  the  burning  process  employed  could 
give  no  more  definite  information. 

(10)  However,  recourses  to  the  microscopic  test  for  lime 
showed  that  changes  in  the  rate  of  set  were  brought  about  largely 
by  altenations  in  the  condition  of  the  free  lime  and  that  the  work 
on  the  ordinary  commercial  cements  would  have  to  be  supple- 
mented with  a  study  of  known  and  selected  material  ground, 


v]  Congress  of  Applied  Chemistry  97 

plastered  and  seasoned  under  known  conditions.  For  this  pur- 
pose large  quantities  of  fresh,  nonseasoned  clinkers  were  obtained 
from  three  manufacturers  who  were  selected  in  order  to  obtain 
standard  cement  with  characteristically  different  chemical  and 
physical  properties. 

(11)  Manipulated  in  the  ordinary  way,  the  setting  properties 
of  these  non-seasoned,  non-plastered  cements  were  essentially 
the  same,  the  plasticity  being  poor  and  the  set  abnormal  and  ap- 
parently slow  and  erratic.     Further  study  showed  that  in  reality 
these  products  set  so  quickly  that  they  became  regauged  by  any 
ordinary  process  of  manipulation  and  that  there  was  an  imme- 
diate generation  of  much  heat  as  soon  as  the  water  was  added. 
Part  of  the  heat  generated  was  due  to  the  hydration  of  free  lime 
and  part  to  the  setting  of  the  cement. 

(12)  A  study  of  the  effects  of  plaster  on  the  nonseasoned 
material  showed  the  following: 

(a)  As  the  amount  of  plaster  used  was  increased  step  by  step 

in  each  cement,  the  initial  set  took  place  earlier,  then 
later,  and  finally  again  earlier.  Also  the  amount  of 
water  required  for  normal  consistency  at  first  decreased 
decidedly,  and  then  later  slightly  increased.  The  same 
quantity  of  plaster  did  not  effect  the  set  and  plasticity 
of  the  different  cements  to  the  same  extent. 

(b)  The  small  amount  of  plaster  used  had  no  appreciable 

effect  upon  the  slaking  of  ignited  lime,  and  therefore, 
did  not  prevent  the  generation  of  heat  due  to  the  slaking 
of  the  free  lime  in  this  material. 

(c)  The  effect  of  minute  quantities  of  plaster  was  to  prevent 

regauging  and  to  produce  in  reality  a  slower  setting 
cement  but  one  which  after  ordinary  manipulation  set 
more  and  more  quickly  until  all  regauging  was  entirely 
eliminated. 

(d)  Further  additions  of  plaster  retarded  the  set,  from  1.5  to 

3  per  cent,  producing  a  maximum  effect.  Beyond  this 
amount  the  natural  tendency  of  plaster  of  Paris  to  set 
quickly  manifested  itself  in  the  combined  results  ob- 
tained and  the  time  of  initial  set  again  approached  a 
maximum. 


98  Original  Communications:  Eighth  International        [VOL. 

(13)  A  study  of  the  effects  of  various  methods  of  seasoning 
either  the  non-plastered  ground  cement  or  clinker  showed  that 
as  soon  as  the  free  lime  had  become  thoroughly  hydrated  less 
water  and  less  plaster  were  required  to  produce  a  normal  paste 
of  standard  consistency  and  set.     The  efficiency  of  the  different 
methods    of    seasoning    depended    entirely    upon    the    relative 
amounts  of  calcium  hydrate  produced  and  maintained,  the  con- 
version into  carbonate  acting  so  as  to  decrease  the  plasticity  and 
the  retarding  influence  of  the  sulphate. 

(14)  A  study  of  the  effects  produced  by  seasoning  plastered 
cements  showed  that  no  radical  difference  was  manifested  if 
plaster  was  added  before  the  cement  had  seasoned. 

(15)  Additional    consideration    and   experiments   proved: 

(a)  That  the  compounds  which  react  with  water  and  cause 

cements  to  set  had  not  been  appreciably  affected  by 
the  atmospheric  influences  which  altered  the  condition 
of  the  free  lime. 

(b)  That  all  hydraulic  compounds  which  cause  cement  to  set 

are  not  affected  to  the  same  extent  by  heat  or  retarders. 

(c)  That  the  normal  rate  of  the  reaction  of  the  compounds 

which  cause  cements  to  set  varies  considerably. 

(d)  That  when  free  calcium  oxide  is  present  and  water  is 

added  the  heat  of  hydration  tends  to  increase  the  natural 
rate  of  set  of  the  hydraulic  compounds. 

(e)  That  a  preliminary  hydration  of  the  free  lime  adds  to  the 

efficiency  of  the  retarder  and  increases  the  plasticity 
of  the  cement. 

(f)  That  the  substitution  of  calcium  carbonate  for  slaked 

lime  tends  to  reduce  the  plasticity  and  decrease  the 
efficiency  of  plaster  of  gypsum  as  a  retarder. 

(g)  That  ultimately,  after  prolonged  exposure,  the  cement 

itself  may  finally  become  practically  inert, 
(h)     That  four  changes  may  occur  in  the  rate  of  set  and  two 
in  the  plasticity,  namely: 

1.  An  acceleration  of  the  set  and  an  increase  in 

plasticity  as  regauging  is  eliminated  as  free 
lime  slakes. 

2.  Then  a  retardation  of  the  set  and  a  further  in- 


v]  Congress   of  Applied  Chemistry  99 

crease  in  plasticity  as  more  free  lime  be- 
comes slaked. 

3.  An  acceleration  of  the  set  and  a  decrease  in 

plasticity  as  the  quantity  of  slaked  lime 
becomes  reduced  by  conversion  into  calcium 
carbonate. 

4.  A  retardation  of  the  set  and  a  further  decrease 

in  plasticity  as  the  cement  after  prolonged 
exposure  tends  to  become  inert, 
(i)     That  these  changes  account  for  all  of  the  variations  met 

with  in  the  action  of  commercial  Portland  cements. 
(j)     That  the  results  and  conclusions  derived  from  the  selected 
material  by  the  method  of  investigation  resorted  to, 
proved  truly  characteristic  of  the  general  nature  of  the 
commercial  products  represented. 

(16)  This  knowledge  led  to  very  definite  results  and  conclu- 
sions concerning  the  practical  control  of  the  setting  properties. 
It  became  evident: 

(a)  That,  whatever  the  influence  of  chemical  composition, 

the  real  phenomena  entering  into  the  reactions,  the 
natural  activity  of  the  setting  compounds  and  the  quan- 
tity and  condition  of  the  free  lime,  and  analysis,  such 
as  is  outlined,  of  the  cement  before  it  is  packed  is  an 
accurate  means  of  ascertaining  the  possible  effects  of 
storage  on  its  setting  properties.  It  will  not  only  in- 
form the  manufacturer  if  the  set  of  the  product  of  his 
kiln  is  capable  of  being  kept  within  normal  or  desirable 
limits  during  the  process  of  ordinary  storage,  but  also, 
will  fix  the  minimum  amount  of  retarder  required  to 
do  so. 

(b)  That  sometimes  a  cement  must  be  seasoned  before  its 

set  can  be  controlled,  but  in  most  instances  this  is  not 
necessary,  and  in  all  instances  the  necessity  for  season- 
ing can  be  avoided  by  proper  burning. 

(c)  That  it  is  the  effects  of  hydration  of  the  free  lime  and  not 

its  conversions  into  carbonate  to  which  the  manufacturer 
must  give  special  consideration. 

(d)  That  proper  packing  is  necessary  for  best  results. 


100          Original  Communications:  Eighth  International       [VOL. 

(e)  That  almost  all  commercial  cements  which  failed  to  pass 
standard  specifications  only  because  of  their  rate  of  set 
would  have  proven  satisfactory  in  all  respects  had  they 
been  seasoned  or  plastered  properly. 

(17)  A  study  of  the  influence  of  fineness  upon  the  rate  of  set 
introduced  no  new  or  unsurmountable  factors  into  the  problem 
of  the  control  of  the  set.     Obviously,  if  a  cement  is  reground  and 
tested  before  the  calcium  oxide  newly  liberated  from  coatings  of 
slag  or  calcium  carbonate  has  become  converted  into  hydrate, 
the  heat  produced  by  the  slaking  of  this  line  will  tend  to  quicken 
the  set.     This  influence  can  be  removed  simply  by  seasoning  the 
cement.     One  other  influence,  namely,  that  due  to  the  increase 
in  the  amount  of  active  cement,  can  not  be  removed  without 
seriously  injuring  the  strength  of  the  material.     However,  in 
most  instances  it  required  only  the  use  of  a  small  additional 
quantity  of  retarder  to  overcome  this  influence,  and  with  few 
exceptions,  it  is  certain  that  manufacturers  can  control  the  set 
of  their  product  even  though  it  is  all  ground  to  an  impalpable 
powder. 

(18)  A  brief  summary  of  all  of  the  results  and  conclusions 
derived  from  this  investigation  could  not  be  made,  but  special 
attention  was  directed  to  the  following: 

(a)  That  manufacturers  especially  should  give  the  subject 

of  partial  regauging  due  consideration  as  such  cements 
although  apparently  slow  setling  at  the  mill  are  apt  to 
be  quick  setting  when  tested  at  their  destination. 

(b)  That  the  policy  of  using  a  minimum  amount  of  gypsum 

has  often  resulted  in  quick  setling  material  where  0.5 
per  cent,  of  additional  retarder  would  have  prevented 
all  trouble. 

(c)  That  this  work  establishes  many  definite  facts  and  clears 

up  much  misconception  concerning  the  efficiency  of 
various  methods  of  treating  the  clinker.  Taking,  for 
instance,  the  investigation  of  H.  Spencer  Conover,1  his 
results,  far  from  indicating  that  the  more  quickly  the 
clinker  cooled,  the  more  slowly  the  cement  set,  only 


iCement  Age  (1905),  3,  479-86. 


v]  Congress  of  Applied  Chemistry  101 

offer  additional  corroboratory  evidence  to  the  conclu- 
sions arrived  at  by  our  own  experiments.  On  the  other 
hand,  adequate  reasons  are  given  for  the  beneficial  re- 
sults obtained  by  H.  K.  G.  Bamber's  method1  of  grind- 
ing the  clinker  in  the  presence  of  a  limited  amount  of 
live  steam.  Taking  into  consideration  only  the  hydra- 
tion  of  the  free  lime  this  method  is  more  efficient  than 
aeration.  It  is  suggested  that  even  greater  efficiency 
might  be  obtained  by  dropping  the  red-hot  clinker  into 
water  as  soon  as  it  leaves  the  rotary  kiln. 

PART  IV 
The  Strength  of  Portland  Cement 

(19)  A  study  of  the  divers  conclusions,  uncertainty  and  con- 
fusion concerning  the  cause  and  significance  of  results  obtained 
from  testing  the  strength  of  Portland  cement,  resulted  in  the 
following  observations. 

(a)  That  were  it  not  for  their  characteristic  drop  in  tensile 

strength,  high  testing  rotary  cements  would  meet  with 
universal  approval  and  the  problem  of  cement  testing 
and  standardization  would  be  greatly  simplified. 

(b)  That  the  failure  to  establish  a  more  definite  relationship 

between  the  tensile  and  compressive  strength  can  be 
attributed  partly  to  differences  in  the  size  of  test  speci- 
mens, the  large  cubes  or  cylinders  usually  used  for  test- 
ing the  strength  under  compression  being  less  apt  to 
show  the  peculiarities  of  cement  than  the  small  bri- 
quettes used  for  tension  test. 

(c)  That  results  obtained  by  crushing  small  specimens  show 

the  up  and  down  values  common  to  tension  test  curves, 
but,  that  even  when  all  specimens  are  practically  the 
same  size,  the  values  do  not  go  up  and  down  coinci- 
dently. 

(d)  That  tension  tests  are  as  useful  as  determinations  of  com- 

pressive strengths,  and  that  a  retrogression  in  the  values 

Concrete  and  Const.  Eng.  (1909),  4,  196. 


102          Original  Communications:  Eighth  International        [VOL. 

of  either  occurs  only  when  due  to  the  development  of 

undesirable  contending  influences. 

(20)  It  was  thought  that  a  study  of  the  hardening  properties 
of  the  numerous  commercial  Portland  cements  at  our  disposal 
together  with  the  available  knowledge  concerning  their  chemical 
composition  would  give  valuable  and  more  definite  information 
on  several  essential  points.  This  preliminary  investigation  soon 
led  to  the  following  results  and  conclusions. 

A.  Concerning  the  typical  curve  of  strength  as  described  by 
W.  P.  Taylor:1 

(a)  That  the  characteristic  fluctuations  in  strength  could  not 
be  attributed,  as  suggested  by  Taylor,  to  the  different 
rates  of  hardening  of  the  different  constituents  of  the 
cement  and  to  a  deterioration  of  the  sulphates  and 
aluminates. 

B.  Concerning  the  noteworthy  deductions  and  conclusions 
arrived  at  by  W.  A.  Aiken2  which  relate  to  the  influence  of  ulti- 
mate chemical  composition  and  early  gain  in  strength: 

(a)  That  it  soon  became  evident  that  the  development  and 

the  maintenance  of  the  early  strength  did  not  depend 
upon  the  early  gain  in  strength,  or  upon  a  narrow  limit- 
ation of  the  percentage  of  calcium  oxide,  the  value  of 
the  silica-alumina  ratio,  the  hydraulic  modulus,  or  on 
any  other  available  chemical  information.  In  fact, 
in  most  instances  it  was  found  possible  to  change  the 
natural  effect  of  all  of  these  factors  by  altering  the  de- 
gree of  burning,  the  fineness  of  either  the  raw  material 
or  the  finished  product,  and  by  seasoning  the  cement 
or  the  clinker  in  a  different  manner  or  to  a  different 
extent. 

(b)  That  as  stated  by  E.  B.  M'Cready,3  "the  rate  at  which 

the  disruptive  strain  due  to  free  lime  increases  in  dif- 
ferent samples  under  various  conditions  of  burning, 
grinding  and  testing,  is  the  kernel  of  the  nut  which  we 


.  Soc.  Test,  Mat.  (1903),  3,  413. 
2Cement  Age  (1903),  1,  75. 
demerit  Age  (1905),  5,  339. 


v]  Congress  of  Applied  Chemistry  103 

ought  to  crack  before  placing  too  much  reliance  on  rules 
deduced  simply  from  analyses  or  percentages  of  gain." 
(c)     That  a  consideration  of  the  physical  and  chemical  prop- 
erties of  free  and  combined   calcium    oxides    provide 
in  itself  sufficient  proof  that  here,  as  in  the  setting 
phenomena,  different  degrees  of  grinding,  burning,  and 
seasoning  produce  marked  effects  to  which  can  be  attrib- 
uted the  primary  influences  which  operate    to    cause 
uncertainty  as  to  the  development  of  strength. 
(21)     Concerning  the  effects  of  anhydrous  free  lime,  a  consid- 
eration of  its  chemical  and  physical  properties  makes  the  follow- 
ing evident: 

(a)  That  it  is  the  lime  which  fails  to  slake  before  the  cement 

has  set  that  is  apt  to  cause  disintegration  or  weakness. 

(b)  Lime  burned  at  a  white  heat  hydrates  much  more  slowly 

and  expands  50  per  cent,  more  than  lime  burned  at  a 
low  heat. 

(c)  That  owing  to  the  impermeable  nature  of  indurated  neat 

cement  the  expansion  due  to  free  lime  will  not  develop 
equally  in  specimens  of  different  shape,  size,  volume, 
or  density. 

(d)  That  this  expansive  force  manifests  itself  less  in  lean 

than  in  rich  mortars  and  that  the  action  of  free  lime  is 
rendered  less  harmful  by  using  sands  containing  poz- 
zuolana. 

(e)  That  when  the  cement  is  submerged  in  cold  water  "this 

disruptive  force  may  not  develop  its  full  value  in  a 
month  or  a  year."1 

(f)  That  in  air,  sintered  lime  slakes  much  more  slowly  than 

in  water. 

(g)  That  owing  to  the  impermeable  coating  of  slag  and  cal- 

cium, carbonate  boiling  water  may  fail  immediately  to 
attack  the  free  lime  in  aerated  cement  unless  regrind- 
ing  has  been  resorted  to. 

(h)     That  the  force  which  operates  to  cause  cements  and 
mortars  to  disintegrate  will  not  become  apparent  to 


.  B.  M'Cready.    Cement  Age  (1905),  5,  339. 


104  Original  Communications:  Eighth  International       [VOL. 

the  eye  until  it  has  overcome  the  strength  of  cohesion 
developed  by  other  constituents  in  the  cement.  That, 
nevertheless,  if  a  hardened  cement  contains  anhydrous 
free  lime  the  strength,  which  otherwise  it  is  capable  of 
developing  and  maintaining,  is  certain  sooner  or  later 
to  be  affected  when  this  lime  is  permitted  to  slake. 

(22)  A  similar  consideration  of  the  properties  of  slaked  lime 
makes  it  evident  that  its  influence  upon  the  strength  also  depends 
upon  the  nature  of  the  cement  and  the  manner  in  which  it  is  used. 
It  does  not  possess  the  ability  to  harden  in  water,  but  hydrau- 
licity  may  be  slowly  imparted  to  it  by  the  presence  of  pulverized 
pozzuolana.     If  permitted  to  absorb  carbon  dioxide  it  has  ce- 
mentive  properties  of  its  own,  but  the  process  of  induration  is 
slow  and  confined  more  or  less  to  exposed  surfaces.     Also,  the 
presence  of  slaked  lime  may  affect  the  strength  of  a  cement  in  a 
mechanical  manner,   inasmuch  as  it  shrinks  very  much  if  per- 
mitted to  dry,  increases  the  plasticity,  and  in  certain  conditions 
decreases  the  permeability. 

(23)  Concerning  the  effects  upon  the  strength  of  various 
combinations  of  calcium  oxide  with  silica,  alumina,  or  iron  oxide 
much  remains  to  be  ascertained.     However,    the  comprehensive 
and  thorough  work  of  0.  Schott,1  E.  D.  Campbell,2  S.  Keissman3 
and  others,  has  been  established  the  following: 

(a)  That  the  pulverized,  fused  or  perfectly  sintered  calcium 

compounds  in  calcareous  cements  possess  the  property 
of  hardening  under  water  without  an  appreciable 
change  in  volume  and  without  the  necessity  of  prelim- 
inary curing. 

(b)  That  with  proper  mixtures,  the  nearer  we  approach  a 

thoroughly  combined  and  fused  clinker  the  less  is  the 
expansion  of  the  resulting  cement. 

(c)  That  since  with  the  silicates  the  strength  increases  as 

the  lime  increases  while  with  the  aluminates  the  oppo- 
site is  true,  and  since  the  high  silicates  and  the  low 


1Cement  and  Eng.  News  (1910),  22,  No.  9-12. 
2Amer.  Chem.  Soc.  (1904),  26,  1273. 
3Cement  and  Eng.  News  (1911),  23,  No,  1-3. 


v]  Congress   of  Applied  Chemistry  105 

aluminates  require  the  greatest  heat,  it  is  evident  that 
high  temperatures  produce  high  strengths. 

(d)  That  the  differences  in  the  physical  properties  of  the 

various  calcium  compounds  account  for  the  failure  of 
ultimate  chemical  analyses  to  reveal  the  true  nature  of 
commercial  cements. 

(e)  That  combined  magnesia  like  combined  lime  has  no  in- 

jurious effect  in  cement. 

(f)  That  the  hardening  process  of  hydraulic  calcium  com- 

pounds is  to  a  large  extent  not  limited  to  exposed  sur- 
faces, but  takes  place  throughout  the  mass,  this  being 
one  of  the  main  reasons  that  good  Portland  cements 
give  more  constant  and  reliable  results  than  other  cal- 
careous cements. 

(24)  A  general  consideration  of  the  physical  and  chemical 
properties  of  hydraulic  limes  of  all  classes  offers  a  remarkable 
demonstration  of  the  properties  of  free  and  combined  lime  which 
have  been  pointed  out  in  the  preceding  pages.  It  shows: 

(a)  That  from  the  low  gravity  and  unreliable  hardening  prop- 

erties of  the  natural  pozzuolane  cements,  we  rise  in 
efficiency  and  usefulness  through  the  hydraulic  lime, 
slag  and  natural  cements  to  the  great  and  reliable 
strength  of  good  Portland  cement,  solely  by  reason  of 
the  condition  of  the  free  and  combined  lime  character- 
istic of  each. 

(b)  That  everburning  natural  cement  is  essentially  under- 

burning  Portland  cement,  and  that  the  evil  effects  re- 
sulting from  either  process  are  due  to  the  production 
of  a  maximum  amount  of  slow  slaking,  sintered  free 
lime  and  free  magnesia. 

(c)  That  a  more  efficient  natural  (or  Roman)  cement  than 

that  produced  at  present  by  burning  cement  rock  in 
set-kilns  could  be  manufactured  by  blending  clay  and 
limestone  in  proper  proportion  and  then  burning  the 
mixture  at  a  low  temperature  in  a  rotary  kiln. 

(d)  That  rapid  cooling  is  an  essential  to  the  efficiency  of  slag 

cement  on  account  of  the  fact  that  its  low  lime  and  high 
silica  and  alumina  contents  are  heated  to  liquefaction. 


106          Original  Communications:  Eighth  International        [VOL. 

(e)  That  rapid  cooling  is  not  an  essential  to  the  preservation 

of  high  limed  silicates  and  low  limed  aluminates  in 
Portland  cement,  because  the  fusion  has  only  reached 
the  incipient  state  and  the  percentage  of  calcium  oxide 
is  high. 

(f)  That  owing  to  the  unequal  degree  of  burning  to  which 

the  raw  material  in  different  parts  of  the  set  kiln  is  sub- 
jected and  to  fuel  contamination  the  aggregate  produced 
by  this  process  usually  consists  of  a  mixture  of  all 
five  classes  of  hydraulic  cements  in  which  the  well  sin- 
tered Portland  cement  clinker,  typical  of  good  rotary 
practice,  predominates. 

(g)  That  the  characteristic  low  early  strength  of  set  kiln 

cement  is  due  to  the  presence  of  the  underburned  ma- 
terial and  not  to  the  slow  cooling  of  the  clinker. 

(25)  These  general  considerations  brought  us  to  the  point 
where  we  were  prepared  to  investigate  more  specifically  the 
occurrence  and  the  cause  of  changes  and  differences  in  the  hard- 
ening properties  of  commercial  Portland  cements.     Obviously, 
the  soundness  of  a  cement  is  a  first  consideration,  and  the  fact 
that  any  tendency  toward  unsoundness  develops  more  slowly 
in  cold  than  in  hot  water,  and  still  more  slowly  in  air,  verifies 
the  previous  statements  concerning  the  properties  and  influences 
of  free  lime.     Obviously,  also,  cements  so  bad  as  utterly  to  dis- 
integrate when  subjected  to  the  normal  tests  for  soundness  need 
no  further  consideration  until  additional  seasoning  enables  them 
to  remain  sound  in  cold  water  or  air. 

(26)  A  study  of  the  effects  of  seasoning  on  the  hardening  prop- 
erties of  cement  produced  from    soft,    decidedly   underburned 
Portland  clinker  revealed  such  erratic  action  that  few  definite 
statements,  concerning  the  strength  could  be  made.     However, 
the  points  worthy  of  emphasis  about  this  material  are: 

(a)  That    nonseasoned,    underburned    Portland    cement    is 

unsound. 

(b)  That  the  underburned  clinker  seasons  readily. 

(c)  That  seasoned  to  soundness  the  cement  hardens  very 

slowly  but  shows  a  steady  increase  apparently  for  an 
indefinite  length  of  time. 


v]  Congress   of  Applied  Chemistry  107 

(d)  That  ordinarily  any  expansion  due  to  free  lime  occurs 
soon  after  the  set,  and  therefore,  if  the  percentage  of 
magnesia  is  low  it  is  safe  to  assume  the  ultimate  sound- 
ness if  the  neat  mortar  does  not  disintegrate  after  the 
usual  28-day  tests. 

(27)  A  study  of  the  effects  of  seasoning  on  the  strength  de- 
veloped by  hard-burned  Portland  cement  showed  entirely  dif- 
ferent characteristics,  namely: 

(a)  That  the  hard-burned  clinker  may,  or  may  not,  produce 

a  cement  which  requires  no  curing  to  enable  it  to  pass 
the  accelerated  test  for  soundness. 

(b)  That   seasoned   or   nonseasoned,   provided   the   cement 

passes  the  hot  tests,  it  may  be  used  with  reasonable 
certainty  of  its  ultimate  soundness;  but  that  with  hard- 
burned  cement  no  reliance  can  be  placed  on  the  normal 
28-day  tests  for  strength  or  soundness,  a  fact  which 
ought  to  be  sufficient  cause  for  the  rejection  of  all  Port- 
land cements  which  fail  to  pass  the  hot  tests. 

(c)  That  under  normal  conditions  the  expansion  due  to  free 

lime  in  indurated  cement  develops  very  slowly,  so  slowly 
in  fact  that  it  may  not  effect  the  early  strength. 

(d)  That  hard-burned  Portland  cement  hardens  very  rapidly 

and  attains  a  great  early  strength,  but  unlike  the  soft- 
burned  product  the  strength  at  the  end  of  years  is 
usually  less  than  at  the  end  of  28  or  sometimes  even  7 
days. 

(28)  A  study  of  the  effects  of  seasoning  on  the  hardening  prop- 
erties of  the  numerous  sound  commercial  Portland  cements  at 
our  disposal  resulted  as  follows: 

(a)  That  the  early  strength  of  even  hard-burned  cements 

can  be  reduced  to  a  low  figure  by  thoroughly  aerating 
the  ground  product. 

(b)  That  even  prolonged  aeration  of  the  ground  product  has 

no  marked  effect  on  the  ultimate  strength. 

(c)  That  this  effect  of  aeration  on  the  strength  results  from 

the  conversion  of  slaked  lime  into  calcium  carbonate 
and  that  the  tendency  of  this  reaction  to  confine  itself 
to  the  surfaces  of  the  individual  particles  of  cement 


108          Original  Communications:  Eighth  International        [VOL. 

fully  accounts  for  the  manner  in  which  the  hydraulic 
properties  are  retarded  rather  than  eliminated. 

(d)  That  owing  to  this  coating  of  carbonate,  much  depends 

upon  the  permeability  and  exposure  of  the  mortar  as 
to  how  quickly  the  inner  active  constituents  of  aerated 
cement  become  indurated. 

(e)  That  the  original  hardening  properties  of  an  aerated,  hard- 

burned  cement  are  restored  almost  entirely  by  regrind- 
ing;  but,  that  while  such  treatment  would  tend  to  in- 
crease the  efficiency  both  in  sand  carrying  capacity  and 
in  constancy  of  strength  and  volume,  it  is  too  expensive 
to  be  practical. 

(f)  That  the  characteristic  drop  in  strength  may  not  be  elim- 

inated even  by  prolonged  aeration. 

(29)  This  knowledge  and  a  little  further  study  of  commercial 
products  showed: 

(a)  That,  although  the  strength  and  even  the  character  of  the 

curve  of  strength  of  any  given  cement  may  be  affected 
to  a  considerable  extent  by  the  method  of  molding 
employed,  the  quality  of  water  or  quality  of  sand  used, 
and  the  exposure  or  seasoning  resorted  to,  still  in 
spite  of  these  variable  factors  certain  characteristics 
influence  the  strength  to  such  an  extent  as  to  be  readily 
apparent. 

(b)  That  a  low  early  strength  always  results  from  premature 

partial  regauging  or  caking,  coarse  grinding,  the  pres- 
ence in  quantity  of  foreign  substances  such  as  clay,  sand 
or  slag,  underburning,  or  excessive  seasoning. 

(c)  That  a  low  early  strength,  provided  the  cause  was  not 

due  to  coarse  grinding,  is  always  associated  with  a  low 
specific  gravity  (dried  at  110°)  and  a  corresponding 
high  loss  by  ignition. 

(30)  These    facts    concerning   the    hardening   properties    of 
underburned  and  hard-burned  Portland  cements,  etc.,  enable  us 
fully  to  designate  the  general  character  of  all  the  commercial 
cements  examined  and  to  account  for  the  general  nature  of  their 
curves  of  strength.     Thus: 

(a)     Adulterated,   coarsely   ground   or   caked   cements   were 


v]  Congress   of  Applied  Chemistry  109 

readily  detected  by  means  of  chemical  or  physical  exam- 
inations. Such  cements  showed  poor  early  and  ulti- 
mate strength. 

(b)  Underburned  cements  when  sound  have  a  low  gravity 

and  the  microscopic  and  chemical  examination  proved, 
as  in  most  instances,  that  the  low  gravity  was  due  to 
underburning  rather  than  to  adulteration  or  excessive 
aeration.  Such  material  hardened  in  the  manner  char- 
acteristic of  seasoned,  underburned  Portland  cement. 

(c)  If  the  cement  was  sound,  a  gravity  above  3.10  was  posi- 

tive proof  of  hard-burning,  and  such  material  always 
showed  the  characteristic  hardening  properties  of  a 
well  sintered  Portland  cement. 

(d)  Intermediate  products  of  the  cement  kilns  were  repre- 

sented by  a  specific  gravity  which  was  neither  high  nor 
low  as  evinced  by  the  fact  that  usually  then  consisted 
of  a  mixture  of  soft  and  hard-burned  cement,  such 
materials  showed  no  definite  character  in  hardening 
properties. 
(31)  These  and  similar  results  cleared  up  all  misconceptions 

regarding   the   development   and   the  significance  of  the  early 

gain  in  strength.     They  showed  conclusively: 

(a)  That  the  efficiency  in  the  early  tests  of  Portland  cements 

depends  primarily  upon  the  thorough  sintering  or  fusing 
of  proper  raw  materials  and  that  the  best  commercial 
practice  in  this  respect  produces  a  sound,  finely  ground 
product  with  a  low  content  of  volatile  constituents  and 
a  specific  gravity  above  3.10  (dried  at  110°,  but  not 
ignited) . 

(b)  That  unfortunately,  it  is  characteristic  of  such  hard- 

burned  material  to  show  considerable  fluctuation  and  a 
decided  decrease  in  strength  after  induration. 

(c)  That   this,   and   the   slowness   with   which   soft-burned 

cements  harden,  make  it  necessary  to  depend  upon 
perfections  in  the  manufacture  of  hard-burned,  sintered 
or  fused  products  for  greater  economic  efficiency  and 
certainty  in  concrete  construction  work. 

(d)  That,   in   order  to   secure  the   desired  permanency  in 


110  Original  Communications:  Eighth  International       [VOL. 

strength,  the  destructive  force  which  apparently  oper- 
ates after  hard-burned  cements  have  become  thoroughly 
indurated  must  be  discovered  and  eliminated. 

(32)  Accordingly,  in  continuing  this  investigation,  we  con- 
fined our  studies  to  a  consideration  of  hard-burned  Portland 
cements.     We  had  measured  the  changes  in  volume  of  bars  of 
neat  and  sand  mortars  of  the  commercial  cements  and  found  a 
very  suggestive  coincidence  in  the  failure  of  prolonged  aeration 
entirely  to  eliminate  free  lime,  the  drop  in  strength  and  an  ulti- 
mate abnormal  expansion  in  a  hard-burned  product.     This  led  us 
to  believe  that  the  fluctuations  in  strength  might  be  due  to  the 
same  internal  strains  which  tended  to  produce  abnormal  changes 
in  volume.    Campbell  and  White1  were  the  first  to  measure  the 
changes  in  volume  due  to  free  lime  in  hard-burned  cement,  and 
although  our  results  verified  their  conclusions  in  most  respects, 
we  found  some  radical  differences,  namely: 

(a)  That  owing  to  its  longer  confinement  in  the  clinkering 

zone,  the  free  lime  in  hard-burned  commercial  products 
slaked  much  less  rapidly  than  that  prepared  in  their 
small  experimental  kiln,  as  long  as  7  months  being  re- 
quired to  slake  all  of  the  free  lime  in  commercial  prod- 
ucts submerged  in  running  water. 

(b)  That,  like  free  lime  and  an  ultimate  drop  in  strength, 

abnormal  expansion  is  not  eliminated  entirely  by  pro- 
longed aeration. 

(c)  That,  like  the  changes  in  the  strength  and  the  effects  of 

free  lime  upon  the  soundness,  much  depended  upon  the 
density  and  permeability  of  the  mortar  as  to  the  extent 
and  nature  of  the  changes  in  volume. 

(d)  That  owing  to  greater  permeability  and  more  uniform 

hydration,  sand  mortars  changed  in  volume  more  than 
the  action  of  the  neat  mortar  indicated. 

(e)  That  contrary  to  the  general  belief,  our  results  indicated 

that  Portland  cements  do  not  expand  in  water  unless 
they  contain  free  lime  (or  free  magnesia). 

(33)  Our  next  experiments  were  made  for  the  purpose  of 


iJour.  Am.  Chem.  Soc.  (1906),  60,  273. 


v]  Congress   of  Applied  Chemistry  111 

ascertaining  the  effects  of  changes  in  volume  on  the  strength. 
The  results  obtained  showed: 

(a)  That  within  the  limits  of  perfect  elasticity,   Portland 

cements  may  show  a  gain  in  strength  in  spite  of  consid- 
erable expansion. 

(b)  That  nevertheless,  the  strength  can  be  increased  by  re- 

ducing the  expansion. 

(c)  That,  as  was  to  be  expected,  there  is  no  direct  relationship 

between  tensile  and  compressive  strengths  during  the 
period  of  time  in  which  the  cements  show  marked 
changes  in  volume. 

(d)  That  there  is  a  marked  relationship  between  the  strength 

in  tension  and  in  compression  after  the  volume  has 
become  constant  and  apparently  no  internal  stresses  are 
operating. 

(e)  That   fluctuations  in  strength   are   caused  by  internal 

strains  resulting  from  the  hydration  of  free  lime  and 
that  within  the  elastic  limit  these  internal  strains  affect 
the  strength  in  tension  and  in  compression  in  a  dissim- 
ilar manner. 

(f)  That  the  early  strength  developed  by  hard-burned  Port- 

land cement  is  the  more  reliable  as  an  indication  of  the 
ultimate  strength  the  less  free  lime  the  material  contains. 

(g)  That  these  results  are  not  contradicted  by  the  experience 

of  the  Society  of  German  Portland  Cement  Manufac- 
turers which  failed  to  establish  any  definite  relationship 
between  the  durability  of  strength  and  any  of  the  so- 
called  accelerated  tests  for  constancy  of  volume,  be- 
cause our  results  apply  only  to  hard-burned  cement. 

(h)  That,  taking  as  an  outside  instance  the  work  of  the  St. 
Louis  Testing  Laboratories,1  there  seems  to  be  a  definite 
relationship  between  the  durability  of  strength  and  the 
results  of  accelerated  tests  of  hard-burned  Portland 
cement. 

(i)  That,  as  the  soundness  test  fails  to  measure  and  often 
even  to  detect  free  lime  or  to  designate  its  condition,  the 

*U.  S.  Geol.  Survey  (1908),  Bull.  No.  331. 


112          Original  Communications:  Eighth  International        [VOL. 

microscopic  test  offers  much  more  reliable  information 
on  this  point. 

(j)  That  we  have  found  this  effect  of  free  lime  so  character- 
istic that  no  28-day,  or  longer,  tests  of  strength  are 
needed  to  determine  the  fitness  of  cements  for  use. 

(k)  That,  provided  that  an  otherwise  satisfactory  cement 
hardens  in  a  desirable  manner  for,  say,  7  days,  and 
furthermore,  that  the  microscopic  tests  show  no  more 
than  a  little  free  lime  after  regrinding  this  cement,  then 
there  need  be  no  doubt  of  the  ability  of  this  material 
to  harden  in  a  satisfactory  manner  with  age.  In  short, 
the  study  of  a  large  number  of  commercial  products  has 
convinced  us  that  we  have  here  the  much  desired  means 
of  ascertaining  the  true  quality  of  Portland  cements 
without  resorting  to  the  prolonged  tests  for  strength. 

(34)  Throughout  this  work  it  was  necessary  to  take  into 
consideration  the  effects  of  the  degree  of  fineness  to  which  the 
cements  had  been  ground.    Obviously,  the  coarse,  inactive  par- 
ticles may  be  considered  as  clinker,  the  finer  grinding  of  which 
produces  a  cement  whose  properties  depend  upon  the  same  con- 
ditions of  composition,  burning,  seasoning,  etc.,  as  that  of  the 
powder  produced  from  large  clinker.     Therefore,  the  only  new 
consideration  which  the  subject  of  fineness  introduces  concerns 
itself  with  the  permanency  of  the  strength  developed  by  the  finest 
and  most  active  particles.    The  results  obtained  proved  the  dur- 
able nature  of  the  indurated  impalpable  powder,  and  taking  into 
consideration,  also,  the  fact  that  free  lime  hydrates  more  readily 
the  finer  its  state  of  subdivision,  the  great  benefits  derived  from 
commercial  fine  grinding  is  readily  apparent. 

(35)  The  foregoing  results  and  observations  concerning  both 
the  temporary  and  ultimate  strength  lead  to  very  definite  con- 
clusions, namely: 

(a)  That  for  greatest  temporary  efficiency  it  is  necessary  to 

grind  fine  and  to  burn  at  a  high  temperature. 

(b)  That  the  endurance  of  the  great  early  strength  thus  ob- 

tainable, the  increase  in  strength  with  age  and  the  con- 
stancy in  volume  will  be  the  more  satisfactory  the  less 
free  lime  (or  magnesia)  the  indurated  cement  contains. 


v]  Congress  of  Applied  Chemistry  118 

(c)  That  Portland  cement  of  the  desired  quality  can  be 

obtained  by  proper  mixing,  hard-burning,  and  fine 
grinding  of  both  the  raw  materials  and  the  finished 
product. 

(d)  That,  as  greatest  efficiency  is  only  obtainable  at  a  cor- 

responding expense  to  the  manufacturer,  cements  should 
be  purchased  on  a  basis  of  quality  rather  than  upon  a 
mere  consideration  of  quantity. 

CONCLUSIONS 

(36)  A  brief  summary  of  all  the  important  conclusions  arrived 
at  can  not  be  made,  the  interdependent  nature  of  such  conclu- 
sions preventing  a  brief  statement  of  facts.  However  assuming 
that  the  quality  in  Portland  cement  which  we  need  is  constancy 
in  volume  and  setting  properties,  and  reliability  in  strength,  and 
that  it  is  of  vital  importance  that  this  material  both  hardens 
rapidly  and  maintains  a  great  strength,  we  believe  that  the 
enforcement  of  the  following  recommendations  will  increase  the 
efficiency  of  the  present  standard  cement  specifications  of  the 
American  Society  for  Testing  Materials. 

A.  Concerning  the  constancy  of  volume : 

(a)  We  can  not  hope  to  secure  the  desired  efficiency  in 

Portland  cement  unless  the  manufacturer  is 
induced  to  burn  his  materials  so  that  no  season- 
ing is  required  to  produce  a  sound  cement. 
Therefore,  it  is  necessary  to  demand  perfect 
soundness  in  conjunction  with  a  high  specific 
gravity,  and  we  recommend : 

(b)  That  failure  to  meet  the  requirements  of  the  ac- 

celerated tests  shall  (in  place  of  "  need  not  "  as 
now  specified)  be  sufficient  cause  for  rejection. 

B.  Concerning  the  specific  gravity: 

(a)  That  the  best  burning  and  proper  storing  produces 

a  product  which  has  a  high  specific  gravity  (or  a 
low  loss  by  ignition) .  Therefore, 

(b)  That  the  specific  gravity  of  the  cement  as  received 

(i.e.,  dried  but  not  ignited)  shall  not  be  less  than 
8 


114          Original  Communications:  Eighth  International        [VOL. 

3.10  unless  the  loss  by  ignition  is  less  than  2.00 
per  cent. 

(c)  That  the  above  recommendation  provides  for  the 

possibility  of  a  well  burned  cement  with  a  lower 
specific  gravity  provided  the  low  gravity  is  not 
due  to  subsequent  absorption  of  volatile  constitu- 
ents; but  our  experience  does  not  include  such  a 
possibility. 

(d)  That  the  clause  "  Should  the  test  of  cement  as 

received  fall  below  this  requirement  a  second  test 
may  be  made  upon  a  sample  ignited  at  a  low  red 
heat "  be  omitted. 

(e)  That  the  clause  "  A  low  specific  grayity  in  con- 

junction with  a  high  loss  by  ignition  is  positive 
proof  of  undesirable  burning,  adulteration  or 
seasoning  "  be  substituted  for  the  present  para- 
graphs concerning  the  significance  of  the  specific 
gravity. 

C.  Concerning  the  fineness : 

(a)  As  the  specifications  now  stand,  there  is  little 

incentive  to  induce  the  manufacturer  to  grind 
to  the  degree  of  pulverization  that  modern  im- 
provements in  grinding  machinery  has  made 
practicable  unless  his  cement  is  so  poor  that 
extreme  fineness  is  necessary  to  enable  it  to  pass 
the  requirements  for  strength  and  soundness. 
Therefore, 

(b)  That  the  cement  shall  leave  a  residue  of  not  more 

than  5.0  per  cent,  by  weight  on  the  No.  100,  and 
not  more  than  20  per  cent,  on  the  No.  200  sieve. 

D.  Concerning  the  tensile  strength : 

(a)  That  the  average  of  at  least  four  briquettes  repre- 
senting at  least  two  separate  mixtures  of  the  same 
sample  shall  be  taken  for  each  test,  excluding 
any  results  which  are  manifestly  faulty. 

E.  Concerning  re  tests : 

(a)  Manufacturers  should  be  impressed  with  the  fact 
that  these  are  minimum  requirements;  that 


v]  Congress   of  Applied  Chemistry  115 

ample  provision  already  has  been  made  in  the 
specifications  for  lack  of  uniformity  in  testing  as 
well  as  in  real  quality;  and  that  we  demand  a 
quality  »o  superior  that,  regardless  of  the  vari- 
able factors,  the  ability  of  the  cement  to  pass  all 
requirements  shall  be  a  certainty.  Therefore, 
(b)  That  the  results  obtained  from  the  original  test 
shall  be  considered  as  final  unless  it  becomes  evi- 
dent that  a  serious  error  in  sampling  or  testing 
has  resulted  in  totally  misrepresenting  the  quality 
of  the  cement.  In  other  words,  that  "  border- 
line "  cements  should  be  avoided  as  much  as 
possible. 

F.     Concerning  the  practical  significance  of  the  above  recom- 
mendations : 

(a)  Manufacturing  conditions  are  such  that  we  can 

not  hope  to  secure  Portland  cement  which  con- 
tains no  free  lime.  Also,  it  is  realized  that  the 
proposed  specifications  are  not  perfect.  How- 
ever, we  believe  that  the  enforcement  of  the 
above  recommendations  will  support  and  pro- 
mote the  best  practice  in  grinding  and  burning, 
and  accordingly,  secure  greater  uniformity  and 
efficiency  than  the  present  specifications. 

(b)  Without  the  hearty,  honest  cooperation  of  both 

manufacturer  and  user  little  can  be  accom- 
plished. The  degree  of  fineness  and  burning  are 
important  financial  considerations  to  the  manu- 
facturer, and  the  consumer  should  buy  on  a 
basis  of  quality. 

(c)  The  testing  of  a  great  number  of  commercial  Port- 

land cements  from  many  parts  of  the  world  has 
convinced  us  of  the  feasibility  of  these  recommen- 
dations from  both  an  economic  and  practical 
standpoint,  and  the  results  obtained  have  repu- 
diated all  claims  to  the  contrary.  For  instance, 
a  certain  manufacturer  in  America  stated  that 
owing  to  a  long  sea  voyage  he  could  not  guar- 


116          Original  Communications:  Eighth  International        [VOL. 

antee  his  cement  to  pass  the  3.10  requirement  for 
specific  gravity.  Our  work  showed  conclusively 
that  cement  stored  in  good  barrels  undergoes 
very  little  change  due  to  atmospheric  influences 
and  many  cements  imported  from  Europe  and 
America  show  consistently  a  gravity  above  3.10 
and  a  low  loss  by  ignition.  There  are  cements 
which  as  stated  in  the  "  Introduction  "  of  our 
work  show  the  most  remarkable  uniformity  in 
physical  properties. 

(37)  We  desire  to  emphasize  the  importance  of  the  calcium 
hydroxide-phenol  microscopic  test  for  free  lime,  as  in  every 
instance  the  physical  and  chemical  properties  of  the  different 
products  examined  demonstrated  the  accuracy  and  usefulness  of 
this  test.  As  stated,  we  believe  that  in  the  hands  of  an  expert 
it  gives  more  definite  and  reliable  information  regarding  the 
constancy  of  strength  and  volume  than  the  usual  28-day  or  even 
3-  or  6-month  tests.  However,  there  is  one  undesirable  feature  to 
this  test;  namely,  that  it  requires  considerable  experience  and 
ability  correctly  to  interpret  the  significance  of  the  phenolate 
crystals  formed  on  the  microscopic  slide.  Therefore,  in  order  to 
make  this  test  generally  practicable  and  universally  dependable 
it  must  be  simplified  or  made  quantitative.  Certainly,  its  possi- 
bilities and  importance  warrant  much  more  extended  research  in 
this  direction  than  we  have  had  opportunity  to  accomplish. 


THE    CONTROL    OF    DUST    IN    PORTLAND    CEMENT 
MANUFACTURE  BY  THE  COTTRELL  PRECIPI- 
TATION PROCESSES 

BT  WALTER  A.  SCHMIDT 
Los  Angeles,  California 

The  control  of  the  dust  arising  from  the  rotary  kilns  in  the 
manufacture  of  Portland  Cement  is  continually  becoming  a  more 
serious  problem.  This  is  partly  the  result  of  the  enormous 
growth  of  the  Portland  Cement  industry  which  now  demands 
factories  of  such  magnitude  that  the  large  volumes  of  gases  leav- 
ing the  stacks  carry  enormous  quantities  of  dust  into  the  atmos- 
phere, but  is  probably  more  directly  attributable  to  the  present 
trend  of  public  opinion,  which  continually  demands  a  more 
thorough  control  of  fumes  and  smokes. 

The  question  of  the  proper  relationships  which  should  exist 
between  the  factory  and  the  surrounding  inhabitants  has  become 
a  very  important  social  problem.  At  the  present  time  a  large 
amount  of  hardship  is  being  caused  by  improper  action  on  one 
side  or  the  other,  often  substantiated  by  our  Courts  on  the  ground 
of  mere  technicalities.  This  is  a  problem  which  should  receive 
the  closest  and  most  thorough  study  by  a  competent  body  in  an 
endeavor  to  establish  such  laws  as  will  draw  a  line  of  equity 
between  the  different  parties  coming  into  contact  through  the 
development  of  our  modern  industries. 

Should  every  smelter,  refinery  and  like  industry  emit  poisonous 
and  noxious  fumes  from  its  stacks  and  all  other  factories  permit 
smokes  and  dusts  to  escape  in  unrestricted  quantities,  life  in  any 
large  industrial  center  would  be  unbearable.  On  the  other  hand, 
however,  most  industrial  furnace  processes  cannot  be  conducted 
without  the  production  of  large  volumes  of  gases  which  usually 
carry  from  the  furnaces  volatilized  materials  and  solid  particles, 
these  solids  being  swept  along  by  the  heavy  rush  of  the  gases. 
As  the  factories  grow  in  size  and  number  the  damage  and  "  nui- 

117 


118          Original  Communications:  Eighth  International        [VOL. 

sance  "  caused  by  the  fumes  and  dusts  usually  assume  most 
aggravating  magnitudes  and,  after  a  certain  mark  is  reached 
control  of  the  annoying  material  in  the  stack  gases  becomes  a 
necessity.  At  the  outset  we  are,  therefore,  confronted  with  two 
conflicting  factors,  first  the  one  from  within  the  factory,  which 
in  many  instances  makes  it  utterly  impossible  to  prevent  the 
formation  of  dusts,  fumes  and  smokes  in  the  manufacturing  proc- 
esses; and,  secondly,  the  one  from  without,  which  makes  it 
equally  impossible  to  permit  these  materials  to  escape  into  the 
air,  due  to  the  damage  to  the  surrounding  country.  A  further 
complexity  arises  from  the  fact  that  the  surrounding  country 
very  often  demands  the  maintenance  of  the  factory  for  its  own 
continued  prosperity. 

It  is  readily  seen,  that  to  permit  a  problem  of  such  conflicting 
interests  to  take  its  course  without  thorough  study  and  guidance, 
is  bound  to  work  hardships  upon  one  party  or  the  other,  and,  of 
necessity,  will  result  in  such  unjust  proceedings  as  have  at  times 
closed  some  of  our  most  important  industrial  establishments  or 
permitted  other  factories  to  continue  causing  damage  to  the 
territory  surrounding  them.  A  vital  question  confronts  the 
people  to-day  in  this  regard,  in  the  establishment  of  a  rational 
relationship  between  the  different  parties,  taking  into  considera- 
tion the  various  questions  entering  into  the  rapid  changes  of  our 
present  day  industrial  development. 

The  problem  of  relationship  between  factory  and  farmer  has 
become  extremely  critical  in  Southern  California  with  the  Cement 
Industry  where  the  dust  arising  from  the  two  large  factories,  the 
Riverside  Portland  Cement  Company  at  Riverside,  California, 
and  the  California  Portland  Cement  Company  at  Colton,  Cali- 
fornia, settled  upon  the  Orange  and  Lemon  groves  in  the  vicinity, 
causing  some  damage.  It  would  be  out  of  place  in  this  paper  to 
comment  upon  the  actual  damage  done,  as  all  of  the  court  testi- 
mony presented  has  so  far  thrown  little  light  upon  actual  results. 
Whether  the  dust  really  does  cause  any  injury  to  the  trees  is  a 
question  of  minor  importance  in  this  particular  locality,  as  the 
dust  makes  the  groves  unsightly  and  the  farmers  are  convinced 
that  actual  damage  has  been  done. 


v]  Congress  of  Applied  Chemistry  119 

The  Riverside  Portland  Cement  Company  experimented  with 
numerous  methods  in  an  endeavor  to  control  the  dust  arising 
from  their  factory,  with  little  encouraging  results,  and  two  years 
ago  the  writer  undertook  the  work  of  applying  the  Cottrell  Elec- 
trical Precipitation  processes  to  this  new  problem. 

The  Cottrell  Processes  were  invented  and  developed  by  Dr. 
F.  G.  Cottrell,  now  of  the  United  States  Bureau  of  Mines,  but 
until  recently  of  the  Chemistry  Department  of  the  University  of 
California.  These  processes  were  first  developed  in  connection 
with  the  problems  arising  in  the  manufacture  of  sulphuric  acid 
by  the  Contact  Process.  After  the  successful  control  of  these 
acid  mists,  the  processes  were  applied  to  smelter  fumes,  aiming 
directly  at  the  control  of  the  sulphuric  acid,  in  these  gases.  The 
first  plant  has  now  been  in  steady  operation  for  over  five  years, 
operating  upon  the  Parting  Flue  in  the  refinery  of  the  Selby 
Smelter  on  San  Francisco  Bay.  The  processes  were  later  applied 
to  the  larger  problem  of  general  smelter  fume  control.  No  at- 
tempt will  here  be  made  to  go  into  detail  regarding  the  work  with 
these  processes  in  this  field,  as  the  early  history  of  the  processes 
was  quite  thoroughly  discussed  in  an  article  published  a  year  ago 
in  the  Journal  of  Industrial  and  Engineering  Chemistry1  and  has 
since  been  extensively  abstracted  in  other  journals.2  Further, 
Mr.  Linn  Bradley  is  presenting  a  paper  to  the  Metallurgical 
Section  of  the  Congress  upon  the  recent  work  done  in  this  field  of 
application. 

In  undertaking  the  application  of  the  Cottrell  Processes  to  the 
problem  of  collecting  the  dust  in  cement  mills,  a  large  number  of 
new  factors  had  to  be  dealt  with,  as  all  work  done  previously  had 
been  conducted  upon  cool  moist  gases  either  containing  large 
quantities  of  water  vapor,  acid  fumes  or  similar  materials,  all  of 
which  gave  distinct  electrical  characteristics  to  the  gases.  The 


JThe  Electrical  Precipitation  of  Suspended  Particles,  Journal  of  Industrial 
and  Engineering  Chemistry,  Aug.  1911. 

2Mining  and  Scientific  Press,  Aug.  26,  1911;  Scientific  American  Supple- 
ment, Sept.  30,  1911 ;  Engineering  and  Mining  Journal,  Oct.  14, 1911 ;  Engineer- 
ing News,  Oct.  26,  1911;  Metallurgical  and  Chemical  Engineering,  March, 
1912;  Cement  and  Engineering  News,  April,  1912;  Rauch  und  Staub,  April, 
1912. 


120          Original  Communications:  Eighth  International        [VOL. 

primary  factors  in  the  cement  work  are  dry  non-conducting  gases, 
non-conducting  dust  particles,  intense  temperatures,  large 
volumes  of  gases  and  large  quantities  of  solid  material  carried 
by  these  gases.  It  is  a  fair  estimate  to  assume  as  an  average 
figure  that  a  rotary  kiln  100  feet  long  and  7  feet  in  diameter, 
oil  fired  as  on  the  Pacific  Coast,  has  a  volume  of  stack  gases  of 
50,000  cubic  feet  per  minute;  the  gases  above  the  combustion 
zone,  in  the  stack,  having  a  temperature  of  about  450°  Centi- 
grade and  carrying  dust  aggregating  between  four  and  five  tons 
per  day  of  twenty-four  hours. 

The  plan  which  was  first  suggested  for  handling  these  gases  was 
to  turn  all  of  the  gases  from  the  entire  factory  into  one  general 
flue  and  conducting  them  to  such  a  point  as  would  bring  the  tem- 
perature within  the  region  of  our  past  experiences.  It  was  soon 
found,  however,  in  our  first  tests  that  the  dry  gases  presented 
entirely  different  electrical  characteristics  than  were  encountered 
in  treating  the  gases  from  smelter  stacks  and  it  was  later  found 
that  the  high  temperature  facilitated  the  uniformity  of  the  elec- 
trical discharge.  The  plan;  therefore,  adopted  was  to  treat  the 
gases  at  as  high  a  temperature  as  was  permitted  by  the  properties 
of  the  structural  material  used  in  the  treating  apparatus.  By 
using  ordinary  steel,  it  is  quite  possible  to  work  at  the  average 
temperature  of  the  stack  gases,  namely  450°  Centigrade,  pro- 
vided however,  that  the  abnormal  temporary  rises  in  the  tem- 
perature in  these  gases  are  prevented.  The  question  necessarily 
arose  regarding  the  possibility  of  maintaining  satisfactory  factory 
operation  if  we  attempted  to  regulate  the  stack  temperature  too 
closely  and  extensive  tests  were  undertaken  in  pyrometric  control 
of  same.  Work  done  during  the  past  year  has  shown  that  by  in- 
stalling recording  pyrometers  in  the  proper  place  in  the  stacks  and 
placing  the  instruments  so  that  the  "  Burners  "  can  keep  close 
watch  upon  them,  it  is  an  easy  matter  to  regulate  the  fires  in  such 
a  way  as  will  give  practically  a  uniform  temperature  in  the  stacks. 

It  was  the  first  plan  at  the  Riverside  Portland  Cement  Com- 
pany to  connect  all  ten  stacks  by  a  common  flue  which  should 
conduct  the  gases  into  a  general  treating  apparatus,  but  the 
factory  engineers  decided  that  it  would  be  preferable  to  maintain 
individual  control  of  the  kilns.  As  the  factory  design  was  such  as 


v]  Congress  of  Applied  Chemistry  121 

to  prevent  installing  this  form  of  apparatus  upon  the  ground,  it 
was  decided  to  allow  the  entire  stack  structure  to  remain  intact 
and  treat  the  gases  after  they  left  the  existing  stacks.  These 
stacks  are  eighty  feet  high  and  a  platform  has  been  constructed 
at  this  level  upon  which  the  entire  apparatus  has  been  placed. 
In  order  to  test  out  what  effect  the  apparatus  has  upon  the  kiln 
conditions,  we  have  passed  the  gases  through  the  treater  and 
directly  into  the  air  alternately  without  having  the  "  Burners  " 
know  of  the  direction  of  flow  of  the  gases.  Sensitive  recording 
pyrometers  failed  to  indicate  any  effect,  either  in  the  temperature 
of  the  stack  gases  or  the  temperature  of  the  burning  zone  in  the 
kiln,  as  given  by  a  radiation  pyrometer. 

It  might  be  well  here  to  say  a  few  words  regarding  the  underly- 
ing principle  of  the  Cottrell  Electrical  Precipitation  Processes, 
for  those  who  are  not  acquainted  with  the  processes  or  who  have 
not  the  time  to  read  the  references  cited.  Stated  in  a  few  words, 
the  principle  consists  of  bringing  the  dust  laden  gases  under  the 
influence  of  a  series  of  electrodes  some  of  which  maintain  a  "  si- 
lent "  or  "  glow  "  discharge.  By  virtue  of  the  discharge,  the  space 
between  the  electrodes  becomes  filled  with  gaseous  ions  and  the 
dust  particles  passing  through  this  space  become  charged  by 
having  these  ions  impinge  upon  them,  imparting  their  ionic 
charges  to  the  particles.  The  charged  particles  are  then  passed 
through  an  intense  electric  field  which  causes  them  to  migrate  in 
the  direction  of  the  field,  which  in  the  commercial  apparatus  is 
arranged  transverse  to  the  direction  of  the  flow  of  the  gases. 
The  dust  particles  are  by  this  action  drawn  out  of  the  gases  and 
deposited  upon  the  electrodes,  the  gases  being  permitted  to  go 
their  way  unaffected  and  emerge  from  the  treating  apparatus 
freed  from  the  solid  particles  which  had  been  held  in  suspension. 

The  distinct  advantage  which  this  process  has  over  the  me- 
chanical processes  arises  from  the  fact  that  the  gases  themselvei 
play  no  part  in  the  action  in  the  treater,  except  as  carriers  of 
electricity.  In  all  mechanical  processes  the  entire  volume  of 
gases  must  be  acted  upon  in  such  a  way  as  to  take  advantage 
of  the  differences  in  specific  gravity  between  the  suspended  par- 
ticles and  the  gases  themselves,  or  some  similar  action.  In  the 
electrical  processes  the  gases  are  permitted  to  pass  through  the 


122          Original  Communications:  Eighth  International        [VOL. 

apparatus  unaffected  while  the  particles  themselves  are  taken 
hold  of  individually  by  the  electrical  field  and  acted  upon  in  such 
a  manner  as  to  draw  them  out  of  the  current  of  advancing  gases 
and  so  as  to  precipitate  them  upon  the  collecting  electrodes. 
In  order  to  maintain  a  definite  direction  of  migration  of  the  dust 
particles,  the  electrodes  must  be  given  an  unidirectional  elec- 
trostatic charge,  which  in  the  commercial  apparatus  is  generated 
by  rectifying  a  high  tension  alternating  current.  In  the  com- 
mercial apparatus  the  potential  varies  under  different  conditions 
from  20,000  to  40,000  volts. 

The  electrode  system  consists  of  two  forms  of  electrodes;  first, 
the  discharge  electrodes,  which  are  made  in  various  forms,  de- 
pending upon  conditions,  but  are  always  of  a  light  construction 
and  are  so  chosen  as  to  maintain  a  heavy  electrical  discharge  from 
them;  secondly,  the  collecting  electrodes  upon  which  the  solids 
are  precipitated.  These  are  usually  of  a  heavy  construction  and 
the  form  and  arrangement  is  so  chosen  that  no  discharge  takes 
place  from  their  surface.  The  two  forms  of  electrodes  are  alter- 
nated across  the  apparatus  with  an  electrode  spacing  of  from  two 
to  six  inches,  this  distance  varying  with  the  conditions  to  be  met. 
A  series  of  these  rows  of  electrodes  is  placed  in  the  treater  so  that 
the  dust  particles  are  brought  under  the  successive  action  of  this 
series  of  electrodes.  The  length  of  the  treater  is  so  chosen  as  to 
affect  the  desired  cleaning  of  the  gases.  The  cross  section  of  the 
apparatus  is  made  such  as  to  bring  a  balance  between  the  two 
forces  acting  upon  the  suspended  particles,  namely,  the  fric- 
tional  force  tending  to  carry  the  solid  particles  along  with  the 
gases  and  the  electrical  force  tending  to  draw  the  suspended 
particles  out  of  the  advancing  current  of  gases. 

In  the  installation  at  the  Riverside  Portland  Cement  Company, 
the  treater  has  a  cross  section  of  12  x  16  feet,  and  an  over-all 
length  of  20  feet.  As  stated  above,  the  apparatus  is  placed  upon 
a  platform  constructed  at  a  height  corresponding  to  the  top  of  the 
original  stacks,  namely,  80  feet  above  ground.  Upon  this  plat- 
form is  placed  a  short  stack  extension  which  extends  through  the 
roof  of  the  building  structure  and  is  supplied  with  a  damper  of 
special  design.  Upon  either  side  of  the  stack  is  placed  a  complete 
electrical  treater  separated  from  the  stack  extension  by  a  large 


v]  Congress  of  Applied  Chemistry  123 

louvre  damper.  By  means  of  these  three  dampers  the  gases  can 
either  be  conducted  through  one  or  the  other  or  both  treating 
chambers  or  emitted  directly  into  the  atmosphere  as  occasion 
may  warrant.  Each  stack  is  equipped  with  two  treaters  so  as  to 
have  an  auxiliary  apparatus  for  each  kiln.  In  case  one  treater 
should  be  shut  down  for  repairs,  cleaning  or  the  like,  the  other 
treater  will  be  able  to  take  care  of  the  gases  with  moderate  effi- 
ciency. Under  normal  conditions  the  gases  will  be  permitted  to 
pass  through  both  treaters,  insuring  a  thorough  cleaning  of  the 
gases.  The  electrode  spacing  is  here  chosen  at  6  inches  and  there 
are  twenty  rows  of  discharge  electrodes  in  series.  The  dust  is 
precipitated  upon  the  collecting  electrodes  which  are  cleaned 
once  every  three  or  four  hours  by  being  given  a  mechanical 
rapping,  this  action  being  made  automatic  in  so  far  that  the 
operator  merely  puts  an  electric  motor  into  operation.  The  dust 
falls  into  hopper  bottoms  from  which  it  is  again  conducted  into 
the  bins  feeding  the  rotary  kilns.  Each  treater  is  supplied  with  a 
small  outlet  stack  20  feet  high  which  is  sufficient  to  compensate 
for  the  resistance  offered  to  the  gases  by  the  treater.  As  stated 
above,  sensitive  pyrometers  do  not  indicate  any  change  of  temper- 
ature in  the  kilns  or  stacks  when  the  gases  are  permitted  to  escape 
directly  into  the  atmosphere  or  are  passed  through  the  treater. 

The  operating  costs  of  the  apparatus  are  low.  A  complete 
treater  of  the  size  described  consumes  approximately  1\  kilowatt 
hours.  This  includes  electrical  energy  for  all  motors.  A  5,000 
barrel  mill  will,  therefore,  consume  approximately  75  kilowatt 
hours  in  an  entire  installation.  The  manual  labor  required  con- 
sists of  one  man  'per  shift,  of  the  character  of  men  ordinarily 
employed  to  run  electrical  mill  machinery.  It  is,  however, 
usually  advisable  to  have  an  extra  man  on  duty.  There  is  no 
deterioration  in  the  apparatus  under  steady  running  and  the 
machinery  is  subject  to  exactly  the  same  wear  as  any  other  piece 
of  electrical  machinery. 

The  progress  of  the  work  at  the  Riverside  Portland  Cement 
Company  can  probably  best  be  illustrated  by  the  series  of  photo- 
graphs shown  herewith  in  which 

No.  1    shows  the  factory  as  it  appeared  in  1910  with  the  experi- 


124  Original  Communications:  Eighth  International      [VOL. 

mental  flue  No.  1  and  laboratory  on  the  ground  in  front  of 

the  building. 

No.  2    shows  experimental  treater  No.  2  on  roof  of  factory. 
No.  3    shows  experimental  treater  No.  3  on  top  of  stack. 
No.  4    shows  experimental  treater  No.  4  also  on  top  of  stack. 
Nos.  5  and  6  show  experimental  treater  No.  4  with  power  "on" 

and  "  off  ",  (pictures  taken  1  minute  apart). 
No.  7    first  part  of  permanent  installation. 
No.  8    view  across  permanent  treater. 

Other  views  will  be  shown  at  the  Congress  as  lantern  slides, 
showing  the  details  of  the  apparatus,  and  the  details  of  con- 
struction will  be  described  in  conjunction  with  these  views. 

One  important  question  which  has  grown  out  of  the  present 
work  at  the  Riverside  Portland  Cement  Company  lies  in  the 
possible  utilization  of  the  collected  material  as  a  source  of  potash 
for  fertilizer  purposes.  This  factory  does  not  use  clay  in  its  raw 
mix  but  uses  a  decomposing  feldspar  which  has  a  considerable 
potash  content.  In  the  .burning  of  the  cement  the  potash  is 
volatilized  and  condenses  again  in  passing  up  the  stack.  The 
greater  part  is  caught  in  the  electrical  treater  along  with  the  dust 
which  gives  a  dust  containing  considerable  potash  value.  Ex- 
periments have  been  conducted  for  some  little  time  in  the  en- 
deavor of  utilizing  this  material  either  directly  as  a  fertilizer 
"  filler  "  or  extracting  the  potash  from  the  material  with  an  aim 
of  obtaining  a  concentrated  potash  salt.  This  work  is  not  suffi- 
ciently far  advanced  to  permit  publishing  definite  figures. 

Dr.  F.  G.  Cottrell,  inventor  of  the  process,  is  presenting  a 
paper  to  this  Congress  before  the  Section  of  Conservation  and 
Political  Economy  upon  what  he  has  termed  "  An  Experiment 
in  Public  Administration  of  Patent  Rights."  This  deals  with  the 
recently  organized  "  Research  Corporation  "  to  which  Dr.  Cot- 
trell and  his  associates  have  given  the  Patent  Rights  to  the  proc- 
esses for  all  of  the  United  States  except  the  six  western  states  and 
the  application  of  the  processes  to  the  Portland  Cement  industry. 
These  latter  rights,  along  with  the  foreign  holdings,  are  retained 
by  the  parent  Companies,  the  Western  Precipitation  Company 
and  the  International  Precipitation  Company,  with  offices  at 
Los  Angeles,  California. 


No.  1. 


No.  2. 


No.  3. 


No.  4. 


No.  5. 


•*"tansfr2 


No.  7. 


No.  8. 


(Abstract) 
GLASS  FORMULAS.— A  CRITICISM 

BY  ALEXANDER  SILVERMAN,  M.  S. 

Professor  of  Analytical  Chemistry  and  Lecturer  on  Glass  Manufac- 
ture, University  of  Pittsburgh,  Pittsburgh,  Pa. 

The  writer  shows  the  tendency  toward  publication  of  many 
incorrect  formulas,  citing  special  cases  from  a  number  of  books 
and  journals,  and  asks  co-operation  of  authors  for  elimination  of 
such  errors  so  as  to  raise  standard  for  manufacture  of  glass,  and 
of  literature  on  this  subject,  to  the  high  plane  occupied  by  other 
exact  sciences. 


125 


THE  VISCOSITY  OF  MOLTEN  GLASSES 

PAPER  I,  THE  VISCOSITY  OF  BORATK  GLASSES 

BT  HOMER  F.  STALBT 
Ceramic  Engineering  Laboratories,  Ohio  State  University 

INTRODUCTION 

The  object  of  this  research  was  to  establish,  in  a  qualitative 
manner  at  least,  the  laws  of  viscosity  for  molten  glasses.  An 
understanding  of  these  laws  is  of  fundamental  importance  to  the 
silicate  industries.  The  viscosity  of  molten  borate  glasses  is 
treated  in  the  present  paper;  investigations  on  silicate  glasses 
are  now  in  progress. 

METHOD 

The  method  used  for  measuring  the  relative  viseosities  of  the 
glasses  was  a  modification  of  that  of  Tamman,  which  has  been 
used  by  Greiner,1  Arndt,2  Doelter  and  Sirk,3  and  others.  The 
principle  involved  is  that  of  measuring  the  time  of  fall  through  a 
certain  distance  of  an  immersed  body  of  given  volume  and  known 
effective  weight.  If  the  weight  is  varied  in  the  same  liquid,  the 
product  of  " weight  X  time"  gives  a  constant  known  as  the 
"  fall-product."  The  "  fall-product  "  has  been  shown  by  Lan- 
denburg4  to  be  proportional  to  viscosity. 

In  this  investigation,  an  analytical  balance,  sensitive  to  0.10 
mg.,  was  fitted  with  a  beam  24  inches  long.  To  one  end  of  the 
beam  was  attached  a  small  scale  pan,  to  the  other  a  platinum  wire 
about  5  ft.  long.  Inserted  near  the  upper  end  of  this  plantinum 
wire  was  a  small  rod  having  two  deeply  ground  grooves  exactly 
1  inch  apart.  These  grooves  served  as  markers  for  getting  the 


JN.  Jahrb.  f.  Mineral,  1906.    II,  p.  152. 
zz.  Electrochemie,  XIII,  p.  578. 
'Monatshefte,  XXXII,  p.  643. 
4Ann.  d.  Physik.  XXI,  287. 


127 


128  Original  Communications:  Eighth  International       [VOL. 

time  of  fall.  The  wire  contained  also  a  small  turn-buckle,  for  use 
in  adjusting  the  height  of  the  plunger.  To  the  lower  end  of  the 
platinum  wire  was  attached  a  platinum  plunger  consisting  of  a 
hollow  cylinder  16.5  X  19  mm.  outside  dimensions,  with  walls 
0.7  mm.  thick,  and  weighing  16.5  grams.  The  hollow  cylinder 
shape  was  adopted  on  account  of  its  giving  a  large  area  for  inter- 
nal friction  in  a  small  volume,  and  at  the  same  time  being  easy  to 
clean.  The  charge  was  contained  in  a  platinum  crucible  4  c.  m. 
in  diameter  by  6.5  high.  The  heating  was  done  in  part  in  a 
platinum  resistance  furnace  and  in  part  in  a  small  gas-fired  pot 
furnace.  We  were  able  to  get  check  readings  on  the  same  glass 
heated  by  the  two  methods. 

The  temperatures  were  determined  by  a  pt — pt  rd  couple, 
immersed  naked  in  the  melt,  and  a  Hartmann  and  Braun  gal- 
vanometer. The  couple  and  galvanometer  were  standardized 
against  a  similar  outfit  calibrated  by  the  U.  S.  Bureau  of  Stand- 
ards and  kept  at  the  University  for  standardization  purposes. 

The  time  of  fall  was  obtained  by  means  of  a  telescope,  sighted 
on  the  small  marked  rod,  and  a  stop-watch,  reading  0.10  seconds. 
Care  was  taken  to  have  the  rod  well  in  motion  before  the  first 
mark  crossed  the  hair  line  of  the  telescope.  Parallax  was  avoided 
by  having  a  scale  fixed  rigidly  to  a  table  behind  the  small  rod. 
This  method  of  obtaining  the  time  of  fall  was  considered  superior 
to  an  automatic  recording  device  in  conditions  such  as  these 
in  which  the  time  interval  varied  largely  and  in  which  there  was 
considerable  variation  in  temperature  that  would  be  liable  to 
throw  out  of  order  any  delicate  mechanism.  To  an  experienced 
observer,  any  variation  in  rate  of  fall,  due  to  sticking,  etc.,  dur- 
ing one  reading  is  easily  discernible. 

The  charges  were  melted  in  the  platinum  crucible  and  carried, 
with  frequent  stirring,  to  a  temperature  above  that  at  which  any 
determinations  were  made  and  sufficiently  high  to  render  them 
fluid  enough  to  insure  homogeneity.  In  all  cases  beautifully 
transparent  liquids  were  secured.  In  a  number  of  cases,  after  a 
series  of  determinations  a  charge  was  allowed  to  cool,  was  re- 
ground,  and  another  series  run  the  next  day.  In  these  cases  check 
results  were  obtained.  We  were  also  able  to  get  good  check 
results  on  separate  charges  of  the  same  composition,  the  deter- 


v]  Congress  of  Applied  Chemistry  129 

minations  being  run  at  intervals  of  several  months.  All  readings 
were  taken  as  the  temperature  was  lowered  step  by  step.  On 
changing  the  temperature,  an  interval  of  half  an  hour,  during 
which  the  charge  was  frequently  stirred,  was  allowed  to  elapse  in 
order  to  bring  the  whole  charge  to  a  uniform  temperature. 

MATERIALS 

The  materials  used  were  B203  3  H20,  Ba  CO3,  Ca  CO3,  Sr  CO3, 
Mg  CO3.  The  purest  materials  obtainable  were  used.  Analyses 
showed  that  none  of  them  contained  more  than  a  few  thousandths 
of  one  per  cent,  impurities. 

VOLATILIZATION  OF  B203 

In  order  to  allow  for  differential  volatilization  of  B203,  the 
various  glasses  were  analyzed  after  the  determinations  were 
finished.  It  was  found  that  differential  volatilization  has  taken 
place  only  in  the  mixtures  containing  less  than  0.5  formula  weights 
of  base  to  1  B203.  The  composition  listed  as  0.0272  Ba  O  1  B2O3 
was  weighed  out  to  contain  0.25  Ba  0,  and  the  one  listed  as 
0.1787  Ba  O  1  B203  was  weighed  out  to  contain  0.16f  Ba  O. 
Any  loss  that  took  place  in  compositions  containing  0.5  formula 
weights  or  more  of  base  must  have  consisted  of  volatilization  of 
borates  and  not  of  B203  alone. 

THE  RESULTS 

A  summary  of  the  results  obtained  is  given  in  the  accompanying 
tables  and  curves.  The  individual  determinations  checked  as 
closely  as  could  be  hoped  for,  considering  the  nature  of  the 
liquids  and  the  temperatures  employed.  In  no  case  did  an 
individual  reading  vary  from  the  mean  more  than  5%,  and  in  the 
large  majority  of  cases,  the  maximum  variation  from  the  mean 
was  less  than  2%. 


130 


Original  Communications:  Eighth  International        [VOL. 


B203 


TABLE  I. 


0.0272  BaO,     1     B2O3 


Temperature 
Degrees  Centi- 
grade 

Overweight 
in  Grams 

Number  of 
Readings 

Fall  Product  in 
Grams  x  0.10 
Seconds 

Fall  Product 
Average 

Temperature 
Degrees  Centi- 
grade 

_a 

Is 

11 

o 

"°  & 
Jl 
|l 

Fall  Product  in 
Grams  x  0.10 
Seconds 

Fall  Product 
Average 

708 

7. 

4 

1799 

1799 

1000 

4. 

5 

248 

722 

10. 

4 

1445 

1445 

6. 

4 

254 

251.0 

750 

5. 

4 

1110 

1110 

1138 

2. 

5 

110 

764 

7. 

4 

973 

3. 

4 

111 

110.5 

10. 

4 

968 

970 

1180 

2. 

4 

85 

805 

3.75 

5 

754 

3. 

4 

85.5 

85.0 

3 

755 

754.5 

1236 

2. 

4 

70 

820 

2.5 

3 

715 

715 

3. 

4 

69 

69.5 

860 

2.5 

4 

610 

1333 

1. 

4 

49 

3.75 

4 

613 

1.5 

4 

48 

48.5 

5. 

4 

612 

612 

935 

7. 

4 

435 

10. 

4 

441 

A  or\  er 

438 

0.1787  BaO,  1  B2O3 

940 

2.5 
3.75 

4 
4 

430.5 
431 

903« 

3. 

5 

227 

5. 

4 

432 

431 

4. 

4 

228 

227.5 

955 

7. 

4 

401 

401 

917 

3. 

4 

209 

972 

5. 

4 

375 

375 

4. 

4 

210 

209.5 

1000 

2.5 

5 

340 

1000 

1.5 

10 

76 

3.75 

£ 

326 

2. 

4 

77 

76.5 

5. 

5 

328 

331 

1042 

1. 

4 

40 

1077 

4. 

4 

247 

1.5 

5 

39.2 

39.6 

5. 

8 

245 

246 

1152 

0.5 

4 

17.12 

1111 

3. 

5 

214 

0.7 

4 

17.15 

17.13 

4. 

4 

216 

215 

1265 

0.4 

5 

10.0 

1194 

2. 

4 

146 

0.5 

4 

10.0 

10.0 

3. 

4 

144 

145 

1360 

0.3 

4 

7.35 

1250 

1.5 

7 

127.5 

0.4 

4 

7.20 

7.27 

2. 

4 

127 

127 

1347 

1.5 

4 

104.5 

2. 

4 

102.5 

103.5 

v] 


Congress  of  Applied  Chemistry 


131 


TABLE  II 


0.5  BaO,  1  B20S 


1  BaO,  1  B203 


»73 

ft 

.a 

j  n 

|| 

O    00 

M 

|| 

Product  in 
ams  z  0.10 
Seconds 

B 

Qi  *> 

imperature 
rees  Centi-N 
grade  n 

arweight  in  N 
Grams 

*O   03 

Product  in 
ams  x  0.10 
Seconds 

11  Product 
Average 

P| 

0 

K 

15 

5T 

s| 

6 

* 

2° 

£ 

915 

1.5 

4 

163.00 

1165 

0.3 

5 

3.51 

3.51 

2.0 

4 

164.50 

164.00 

1220 

0.2 

4 

3.20 

1025 

0.3 

5 

18.00 

0.3 

3 

3.10 

3.15 

0.4 

6 

18.06 

18.03 

1275 

0.2 

5 

2.88 

1140 

0.2 

5 

5.22 

0.3 

4 

2.88 

2.88 

1165 
1220 

1275 

0.3 
0.2 
0.2 
0.3 
0.2 

3 
5 
5 
4 
4 

5.15 

4.20 
3.80 
3.90 
3.60 

5.18 
4.20 

3.85 

1.56  BaO,  IBaO, 

0.3 

4 

3.68 

3.64 

985 

0.2 

4 

5.25 

5.25 

1330 

0.2 

4 

3.50 

1010 

0.2 

4 

4.05 

0.3 

4 

3.60 

3.55 

0.3 

4 

4.20 

4.12 

1065 
1165 
1275 

0.2 
0.3 
0.2 
0.3 
0.2 

4 

4 
4 
4 
5 

3.60 
3.72 
3.10 
3.12 
2.80 

3.66 

3.11 
2.80 

0.661  BaO,  1  BzOs 

1100 
1125 

1165 

0.2 
0.2 
0.3 
0.2 
0.3 

4 
6 
4 
4 

4 

7.25 
5.00 
5.18 
3.75 
3.72 

7.25 
5.09 
3.73 

2  BaO,  1  B2OS 

1220 

0.2 

5 

3.40 

1165 

0.2 

4 

3.02 

0.3 

4 

3.45 

3.42 

0.3 

4 

3.00 

3.01 

1292 

0.2 

5 

3.12 

1220 

0.2 

4 

2.85 

0.3 

4 

3.30 

3.21 

0.3 

4 

2.85 

2.85 

1275 

0.2 

4 

2.65 

* 

0.3 

4 

2.66 

2.655 

132          Original  Communications:  Eighth  International        [VOL. 


TABLE  III 


0.5  CaO,  1  B203 


0.25  CaO,  BaO,  1  B2O3 


Temperature 
Degrees  Centi- 
grade 

Overweight  in 
Grams 

Number  of 
Readings 

.9 

if 

-8 

3  <D 
If 

r 

Temperature 
Degrees  Centi- 
grade 

.a 

M  w 

!o 

0 

|l 
fc 

Fall  Product  in 
Grams  x  0.10 
Seconds 

Fall  Product 
Average 

1138 

0.5 

4 

17.0 

17.0 

1042 

1.0 

4 

59.0 

59.0 

1170 

0.3 

4 

12.075 

1055 

1.0 

4 

45.0 

0.5 

4 

12.00 

12.04 

1.5 

4 

45.4 

45.2 

1220 

0.3 

4 

6.3 

6.3 

1070 

1.0 

4 

32.0 

1236 

0.2 

4 

5.0 

5.0 

1.5 

4 

31.5 

31.75 

1275 

0.15 

5 

3.03 

1152 

0.3 

4 

8.1 

0.2 

5 

3.00 

3.015 

0.4 

4 

8.2 

8.15 

1347 

0.15 

4 

2.55 

1180 

0.2 

4 

6.15 

0.2 

4 

2.60 

2.575 

0.3 

4 

6.19 

6.17 

1222 
1265 

0.15 
0.20 
*0.15 
0.20 
0.10 

4 
4 
4 
4 
5 

4.65 
4.60 
4.58 
4.50 
3.42 

4.58 

0.5  SrO,  1  B2O3 

1044 

3.0 

5 

77.5 

77.5 

0.15 

4 

3.45 

3.435 

1055 

2.0 

4 

71.0 

71.0 

1305 

0.10 

4 

3.00 

1165 

0.4 

4 

16.0 

0.15 

4 

3.08 

3.04 

0.5 

4 

16.0 

16.0 

1361 

0.10 

4 

2.92 

1220 

0.3 

4 

8.4 

0.15 

6 

2.85 

2.89 

1265 
1347 

0.4 
0.2 
0.3 
0.15 
0.2 

4 
4 
4 
6 
6 

8.4 
5.95 
6.15 
4.50 
4.48 

8.4 
6.05 
4.49 

*Different    melt    from    that 
giving  the  two  readings  above 

An  attempt  was  made  to  obtain  determinations  on  a  glass  of 
the  composition  0.5  Mg  O  1  B2O3.  It  was  found  that  the  plunger 
dropped  slowly  through  the  upper  layer  of  glass  and  very  rapidly 
through  the  lower  layer,  indicating  that  the  glass  consisted  of  two 
non-miscible  liquids.  Reference  to  the  literature  confirmed  this 
supposition  for  it  has  been  shown  by  Guertler1  that  this  com- 
position forms  a  pair  of  non-miscible  liquids. 

*Zt.  Anor.  Chemie,  XL,  225. 


v] 


Congress  of  Applied  Chemistry 


133 


CONCLUSIONS 

I.  The  viscosity  of  molten  borate  glasses  decreases  at  a  slowly 
decreasing  rate  with  increase  of  temperature.  In  other  words,  the 
viscosity  is  a  hyperbolic  function  of  temperature. 


700 


II.  Each  glass  has  a  characteristic  rate  of  decrease  of  viscosity 
with  temperature.  The  more  viscous  the  borate  at  low  tempera- 
tures, the  more  rapid  is  the  rate  of  decrease  with  rise  of  tempera- 


134          Original  Communications:  Eighth  International        [VOL. 

ture.  The  result  is  that  the  viscosities  of  a  series  of  borate  glasses 
may  vary  widely  at  low  temperatures  but    converge    rapidly 


950 


/300 


toward  what  is  practically  a  minimum  as  the  temperature  is 
raised.    (See  figures  I,  II,  and  IV.) 

III.  The  viscosity  of  B2O3  is  greater  at  any  given  temperature 
than  any  mixture  of  B203  with  a  basic  oxide  studied. 


v] 


Congress   of  Applied  Chemistry 


135 


IV.  In  a  series  of  mixtures  of  B2O3  with  Ba  O,  the  viscosity 
decreased  continuously  with  increase  of  Ba  O.  No  minimum 
points  in  viscosity-composition  curves  were  found.  (See  Figures 
I  and  II). 

FIG.  3 


/300 


TOO 


V.  In  mixtures  between  B2O3  and  0.5  Ba  0  1  B2O3,  the  decrease 
of  viscosity  is  out  of  proportion  to  the  percentage  or  molecular 
amount  of  Ba  0  present,  the  first  additions  of  Ba  0  having  the 


136          Original  Communications:  Eighth  International        [VOL. 

greatest  effect.    The  viscosity  of  the  mixtures  is  also  less  than 
would  be  calculated  by  the  rule  of  mixtures  from  the  percentage 


amounts  of  B203  and  0.5  Ba  O  B203  present  and  their  respective 
viscosities.  (See  Figures  I  and  VI.)  For  practical  purposes  in 
ceramic  operations,  the  calculated  values  could  not  be  used. 


Congress  of  Applied  Chemistry 


137 


VI.  In  mixtures  of  B203  and  Ba  0  in  which  the  compositions 
vary  from  0.5  Ba  0  1  B2O3  to  2  Ba  O  1  B3O3,the  viscosity  decreases 
slowly  with  increase  of  Ba  O,  and  in  almost  direct  proportion  to 
the  amount  of  Ba  0  present.  The  viscosity  of  mixtures  falls 


/J00\ 


slightly  below  the  calculated  additive  values  for  the  definite 
compounds.  For  practical  purposes,  the  calculated  values  could 
be  used. 

jjjiVIL  The  viscosity  at  various  temperatures  of  a  mixture  in 
equal  molecular  proportions  of  0.5  CaO  B203  and  0.5  Ba  O  B2O, 
falls  very  slightly  below  the  calculated  additive  values  for  the 


138          Original  Communications:  Eighth  International        [VOL. 

percentage  amounts  of  the  two  end  members.    (See  Figure  IV.) 
For  practical  purposes,  the  calculated  values  could  be  used. 

VIII.  There  is  no  relation  between  the  melting  point  line  of  a 
series  of  borates  and  the  lines  indicating  temperatures  of  equal 
viscosity.    Eutectic  composition  occur  at  median  points  on  the 
viscosity  line  and  are  of  no  special  significance.1     (See  Figure 
III.2).    In  mixtures  of  Ba  O  and  B2O3  containing  more  than  0.5 
Ba  O  to  1  B203,  the  lines  indicating  temperatures  of  equal  vis- 
cosity are  straight  and  roughly  parallel.      (See    Figure   III.) 
In  mixtures  containing  less  than  0.5  Ba  0  to  1  B208,  the  lines  are 
parabolic  and  roughly  parallel.    (See  Figure  V.) 

IX.  The  fact  that  mixtures  of  B2O3  with  0.5  Ba  0  B2O3  fall  in 
that  class  of  liquid  mixtures  in  which  the  viscosity  is  considerably 
less  than  the  additive  value  would  be  considered,  according  to 
recent  physical  chemical  thought,3  as  an  indication  that  consider- 
able dissociation  of  one  or  both  end  members  has  taken  place  on 
mixing.    In  view  of  the  facts  brought  out  in  regard  to  0.5  Ba  O  1 
B2O3  in  VI  and  VII,  we  are  led  to  make  a  provisional  assumption 
that  B2O3  alone  is  a  polymerized  substance  and  in  these  mixtures 
is  broken  down,  due  to  the  presence  of  a  base,  into  more  simple 
molecules. 

Likewise  the  fact  that  mixtures  of  borates  containing  0.5 
molecules  of  base  to  1  B2O3  give  viscosity  values  that  fall  but 
slightly  below  the  additive  value  would  be  taken  as  an  indication 
that  slight  dissociation  has  taken  place  on  mixing. 

The  conclusions  stated  under  this  number  (IX)  are  given,  not 
as  a  definite  contribution  to  our  knowledge  of  the  physical 
chemistry  of  borate  glasses,  but  as  a  possible  explanation  for  the 
difference  in  behavior  of  the  two  classes  of  mixtures. 

My  thanks  are  here  given  to  Dr.  W.  E.  Henderson,  Professor 
of  Inorganic  and  Physical  Chemistry  in  the  Ohio  State  University, 
for  many  valuable  suggestions  given  during  the  progress  of  this 
investigation. 

*Cf.  Trans.  Amer.  Cer.  Soc.,  XIII,  p.  675. 

2The  "  Freezing  Point  Line  "  is  taken  from  Guertler.  Zt.  Anorg.  Chemie, 
XL,  352. 

3See  Smiles  "The  Relations  Between  Chemical  Constitution  and  Some 
Physical  Properties,"  pages  78-79. 


GENERAL  INDEX 

TO  THE  TWENTY-FOUR  VOLUMES  OF 

ORIGINAL   COMMUNICATIONS 

Volume 

Section 

1 

I. 

Analytical  Chemistry. 

2 

II 

Inorganic  Chemistry. 

3 

Ilia 

Metallurgy  and  Mining. 

4 

Illb 

Explosives. 

5 

IIIc 

Silicate  Industries. 

6 

IV 

Organic  Chemistry. 

7 

IVa 

Coal  Tar  Colors  and  Dyestuffs. 

8 

Va 

Industry  and  Chemistry  of  Sugar. 

9 

Vb 

India  Rubber  and  other  Plastics. 

10 

Vc 

Fuels  and  Asphalt. 

11 

Vd 

Fats,  Fatty  Oils  and  Soaps. 

12 

Ve 

Paints,  Drying  Oils  and  Varnishes. 

13 

Via 

Starch,  Cellulose  and  Paper. 

14 

VIb 

Fermentation. 

15 

VII 

Agricultural  Chemistry. 

16 

Villa 

Hygiene. 

17 

VHIb 

Pharmaceutical  Chemistry. 

18 

VIIIc 

Bromatology. 

19 

VHId 

Biochemistry  including  Pharmacology. 

20 

IX 

Photochemistry. 

21 

Xa 

Electrochemistry. 

22 

Xb 

Physical  Chemistry. 

23 

XIa 

Law  and  Legislation   Affecting  Chemical 

Industry. 

24 

Xlb 

Political  Economy  and    Conservation    of 

Natural  Resources. 

THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN  INITIAL  FINE  OF  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $I.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


DEC301MQM 


LD  21-100m-7, '40 (6936s) 


YC  32281 


246079 


-L- 
- 

UNIVERSITY  OF  CALIFORNIA  LIBRARY 


